When I was in Amsterdam a few years ago I faced pretty aggressive panhandling / scamming; it was that fine line between panhandling and robbery. On the way from central station to my airbnb, I had someone try to follow me and get my address. Another night I had someone waiting outside of my place.

I live in Denver, Colorado and although we have a huge homeless population, I've never had a problem with them. It's mostly just people sitting around asking for money, but I've never been followed or aggressively approached like I have in European cities (Italy was awful).