My Recent Experience with a Transient

I work near the truck stops on the edge of town. We get a lot of homeless here; I guess the truck drivers let them hitch rides or something. Anyway, one day I was gassing up and this man walks up and asks for quarters for air. I tell him that the air machine is free, then he says he really needs the money for gas. Then he gets upset because I ignore him from that point...
I don't give money to people I don't know because most likely they'd just buy alcohol with it. I'd consider giving them food, but I'm rarely in a situation where I have food with me when I encounter someone asking for it.