I think Toronto could give you a run for the money on that claim- we've had a huge Indian population since the 1970s. Some of our neighbourhoods are much improved because of that; it's the standard process of immigrants settling in the cheapest part of town then sprucing it up once they start making money.
What's interesting is that when the Indians were settling in Edison and Iselin starting in the early 1980s, many were well educated folks, who were settling in a blue collar area due to the lower costs of housing. This caused ALOT of resentment towards the "snotty Indians" on behalf of many of the locals. Thinks have simmered somewhat, with Edison acting as the initial area of settlement before the inevitable migration down Route One towards Princeton.
That's a standard process of skilled and motivated immigrants. They tend to be of benefit not only to their neighborhoods, but to our society as a whole, as long as they make reasonable efforts to assimilate into American society.
Other immigrant populations tend to not improve their communities, and those that become successful end up moving out of those communities.