Different places around the world can be considered clean and dirty based on someone's own perception of things, but when it comes to major cities, it's hard to ignore it one way or another. If somewhere is dirty then that's just the way it is, and if somewhere is clean, then you know that the people of that city have worked hard to get it to that point. Nowhere is perfect and that's not exactly a shocking thing to establish, but at the same time, there are definite differences between the good and the bad. For the most part a lot of this is down to human error, and as a sidetrack to that, sometimes it can't be helped by the people of the city - because that's just how things work over there. As humans, our natural instincts should be to look at these things and try to improve them. After all, tourism is a big factor for some of these cities when it comes to revenue and for others, they just need somewhere clean to live in order to keep going. It really isn't rocket science, and we're hoping that an article of this nature can open some eyes to that fact. We aren't narrow-minded enough to believe that this piece alone is going to change things, but this could always help people when it comes to them deciding where they want to travel to next - be it just for a holiday, or to try and help out some of the less privileged areas on the list.

20 CLEAN: Reykjavik, Iceland - A Great Escape

Heading to Iceland feels like you're stepping into some kind of alternate universe, and we aren't talking about Narnia or anything as stereotypical as that. As a country, it may be small, but as a community, their major cities certainly know how to keep things tidy.

Reykjavik, in particular, serves as an exemplary city both in terms of aesthetics and how clean it is. It may not be the biggest and the weather may not always be great, but it progressively gets great reviews from tourists on all fronts, and to be perfectly honest with you, that's good enough for us.

19 DIRTY: Shanghai, China - Unacceptable

Shanghai is the hub for many things in China, from entertainment to business and beyond. Beijing is certainly a handy city and has proven that over the years, but there seems to be a growing popularity associated with Shanghai, and it's certainly hard to ignore that.

Still, that doesn't erase the horrendous pollution problems that the city suffers from, and it's an issue that really does need to be ironed out sooner rather than later. It's all well and good going for a week or so but after that, it's difficult to try and convince expats to want to move over there - which is always going to hurt their image.

18 CLEAN: Singapore - Perfection

Singapore may be the most expensive country in the world, but one glance at the place will soon tell you why. It's efficient, it's clean, and it serves as the benchmark to all over cities around the globe as to what steps need to be taken in order to be deemed 'the best'.

Singapore is just one of those places where it's difficult not to feel safe 24 hours a day, 7 days a week, and for those of you who have spent even a short amount of time there, you'll understand why. Sure, you'll have to fork out a few extra pennies so that you can visit, but it's more than worth it.

17 DIRTY: Seattle, United States - Poor Form

Seattle is one of the most popular cities in the United States of America, and it's not hard to see why. The sporting scene is great, the architecture is magnificent, the atmosphere is always really friendly, and it's just generally a really nice place to visit.

Alas, the pollution problem there is amongst the worst that can be found anywhere around the world, which is actually pretty astonishing. Obviously, you'd have to weigh up just how much these kinds of things matter to you, but in our mind, it ensures that Seattle takes a pretty big hit in our overall rankings.

16 CLEAN: Portland, United States - Showing They Care

A few years ago there was a chance that Portland would've been at the other end of the spectrum on this list, but you have to give props where they're due because the city of Portland has taken big strides towards improving their reputation in this field.

They've put anti-pollution plans in place that seem to have gone down a treat with the community, to the point where they can now be considered one of the cleaner cities on Earth. On top of that, the city itself is pretty remarkable, and it's well worth a visit for a long weekend or two.

15 DIRTY: Venice, Italy - A Huge Letdown

Venice is supposed to be an embarrassment of riches for those who enjoy romantic vacations, and if you spend the majority of your time there on a gondola, then there's a chance that it'll live up to that reputation. If you don't, however, then you may soon spot the truth - or better yet, smell it.

The sewage problem in Venice is one that continues to plague the city as a tourist destination, there's garbage that can be found on every street corner, and the whole place just generally doesn't feel very well looked after. It's a shame, too, because technically speaking, Venice should be an incredible place from top to bottom.

14 CLEAN: Geneva, Switzerland - Lives Up To Expectations

We could've thrown any city we wanted on here from Switzerland, but we've decided to go with Geneva. As a location, it has a high reputation for being a very business orientated city, that also happens to possess some of the best views that can be found in the entire country.

Alas, as expensive as the nation may be, they certainly know how to keep their cities looking fresh. Geneva looks like more of a blueprint than anything else, as if this is the perfect example of what a European city SHOULD look like - and yet, it's completely real. Bravo.

13 DIRTY: Baku, Azerbaijan - Too Much Oil

Baku is a city that's on the up in more ways than one, and that should undoubtedly be something that we're celebrating. Unfortunately, that isn't the case, as they've still got a long way to go before the city can be considered a valid alternative to the current tourist destinations available around Europe.

The oil issue in the city is the biggest problem, and that seems to be leaking into other areas of the environment too (pun not intended). Given the kind of revenue that it generates for the city and the country as a whole, however, it doesn't seem like it's going to slow down anytime soon.

12 CLEAN: Hamburg, Germany - Desperately Underrated

The popular opinion is that Hamburg is a city that's only good for partying and nothing else, but trust us when we tell you that couldn't be any further from the truth. It's one of Germany's shining lights from the tourist attractions to the personalities of those who live there, and we mean that wholeheartedly.

Oh, and did we mention how clean it is? It shouldn't come as a surprise given that the people of Germany are pretty organised for the most part, but Hamburg really does come as a pleasant surprise given its reputation. In fact, we could extend this to most of the country and it'd probably still be accurate.

11 DIRTY: Delhi, India - Unfortunate Stereotypes

We like to avoid stereotypes as much as we possibly can here, and we aren't giving into that, but we are going to say something that some may think serves as the 'easy' way out: Delhi isn't very clean, and it's been that way for a long, long time now.

In fact, the majority of cities in India suffer from this issue, with Delhi, in particular, struggling. It almost feels like they suffer from overpopulation to the point where everything just becomes incredibly congested, and when you look at the figures, it isn't all too hard to imagine that being the case.

10 CLEAN: Copenhagen, Denmark - What A Place

As one of the primary Scandinavian cities that people visit on a day to day basis, Copenhagen is always going to be pretty expensive as an alternative to other cities around Europe you could visit. However, one thing that sets the Danish capital apart is just how unbelievably clean it is.

The title of this article is indeed somewhat lighthearted, but we'd genuinely consider eating off the floor here just to prove a point. Even when it's raining and the weather is miserable it still feels like this is one of the happiest places on Earth, and that's a nice position to be in.

9 DIRTY: Mumbai, India - Must Do Better

Following on from Delhi, we have to admit that Mumbai really does need a spruce up in pretty much every way imaginable. The city has been struggling on a number of different levels for a while now, and the gap between the rich and the poor is probably a big reason for that.

It feels like many of the issues they face could be rectified with a few simple steps, but not everyone is willing to stick out their hand and help with all of that. It sounds sad and in truth, it is, but we're hoping to see Mumbai experience something of a resurgence in the not so distant future.

8 CLEAN: Honolulu, United States - Paradise

Aside from the occasional issue of how much it costs to go there, you won't hear too many people complaining about Honolulu. The city, and the state of Hawaii as a whole is a tremendous place for you to escape all of your troubles in more ways than one.

There's something so infectious about just how laid back it is over there, but thankfully, that doesn't relate to any kind of laziness whatsoever. In fact, it almost seems as if that allows them to work harder to ensure that the standard of living over there is even higher.

So save up your pennies, because Honolulu is a breath of fresh air in every sense.

7 DIRTY: Mexico City, Mexico - Not Up To Scratch

It won't come as much of a shock to some that Mexico City is included on this list, but for them, they just need to put some effort in and the results will come. The lack of clean air there will always be a turnoff, but on top of that, they need to cut out the littering.

It feels like something that is becoming more and more prevalent as the years go on, and they can't allow for that to happen. It's not like the city is a particularly popular tourist destination anyway, but there's always room for them to change that so long as they're willing to put in the work.

6 CLEAN: Helsinki, Finland - The Dark Horse

Helsinki is a city that flies under the radar in more ways than one, but that really shouldn't be the case. The place is absolutely gorgeous and is a wonderful location to visit whether it be in the summer or the winter, and on top of that, they work incredibly hard to make sure it remains clean.

They're very focused on having a great image to portray to travellers and those who are thinking about travelling there, which makes sense. They're still attempting to build themselves up as a viable tourism alternative, so why not care about your appearance? We approve.

5 DIRTY: Port-au-Prince, Haiti - A Sad State

Port-au-Prince has suffered from a variety of different problems over the course of the last few decades, and you could argue that it isn't their fault whatsoever that they've got such a bad reputation in terms of their cleanliness.

Alas, that doesn't mean it's any less true, and the images alone that can be found online tell you all that you need to know. We'd honestly love nothing more than for Haiti as a nation to grow and thrive on its own, but it takes help from outside sources in order to accomplish that. Especially after recent events, we all need to start coming together with issues like this, and we need to do so before its too late.

4 CLEAN: Nottingham, England - Very Impressive

Nottingham is famous for many different reasons, but it isn't often ranked amongst the top places to visit by foreigners when they come over to the United Kingdom. That's a big mistake on their part because the city has plenty to offer, and on top of that, it's one of the cleanest - if not THE cleanest city - in the nation.

It's an extremely popular student city and once you head on round on an open day, you'll soon discover why. It's just so accessible and because of that, it earns its place on this list.

Oh, and if you're into Robin Hood, then that alone should be enough to convince you to go.

3 DIRTY: Karachi, Pakistan - More Attention Required

Pakistan as a nation has always suffered from these kinds of issues, and while they're trying to improve their image as a country, it doesn't feel like they've taken any of the necessary steps to doing so in a realistic manner over the course of the last few years.

The smell of the city puts a lot of people off going there, it's one of the sketchiest places in the world to visit as a tourist, and it feels like there's more talk and less action. It's a shame, but that's just how things are.

2 CLEAN: Vienna, Austria - Romance And Culture

We aren't going to beat around the bush here: Vienna is absolutely beautiful and you need to go there immediately. It may not be the loudest or one of those cities that 'never sleeps', but it still serves as an ideal location for a quick getaway.

From a romance perspective, there are few places that can compare in terms of variety and elegance. You'll be able to enjoy all of the luxuries that they have to offer, and one of the best parts is that you don't need to worry about getting dirty or anything like that. It's a wonderful place, and the word 'underrated' certainly fits the bill here.

1 DIRTY: Paris, France - It’s True, Believe Us

There are so, so many things that we absolutely adore about Paris, and it's almost a shame that we have to include it in this list in this manner. Alas, we can't lie to either ourselves or you guys, which is why we're using Paris as our final entry in the 'dirty' section. From the sewage smell around the city to the constant littering and spitting from locals, the stigma surrounding France's capital is somewhat accurate in this sense. They're certainly taking steps to improve their reputation which is obviously a great thing and remember, that with the cons come the overwhelming pros.