Have a little patience. Next time you're there, take a stroll (actually, don't) through places like Clos Saint-Lazare.
Ever stroll through Bed-Sty, Brooklyn? At night??
The problem general is that vast majority of Americans only see the best part of Paris (Champs Elysee, trip on the Seine river, Louvres, Notre Dame, Cedex de Defense etc...) and they do not see the remaining 70% of Paris where poverty and misery rule. They need to take a trip in the metro to see poverty on people faces. The same things apply for many other European cities.