There was this one bum when I walked into 7/11, his strategy was quite clever. He would open the door for people coming, complement them. Then on the way out open the door again, and then at that time ask for spare change. So.. he does them a service, get's on their good side, then asks for change directly after a purchase when a person has some spare change. It was clever I thought, he was getting quite a few quarters, I gave him 40 cents.
I realized, I'm much less prone to giving out change when a bum is sitting on the side of the street with a cup doing nothing. Not sure why.