i think the same goes with any city in the world, when compared to japan. i recently went with some friends to other cities in asia and they couldn't help but notice how dirtier the cities were, how much louder and more impolite the people spoke, etc etc.
it may be particularly strong in the case of paris because of the stereotypical romantic image. but in general, just about every big metropolitan area has thieves, pollution, etc, while in japan people retain an amazing level of honesty of sense of community. i have friends here that have lost their 6-month bus passes (that cost US$300+), their cell phones, even entire wallets, and anonymous citizens have returned them to the police station, etc.