Philly probably has the most bums but they're very passive. They'll stand outside Wawa and ask you for money, but you can just easily walk past them and ignore them.

When I was in London, I hung out in Piccadilly Circus (Time's Square) and had little kids begging for money and food.It was a shame to see, but I know that they were probably children of gypsies who are too lazy to go out and beg.