Do you ever donate to the homeless? (maybe explain?)

I had a field trip to Portland, Oregon today, and there were so many homeless people there. It kinda made me sad, but there was this one guy in front of Powell's Book Store who was just playing his guitar. His little sign said he was homeless, wanted to raise $18 to buy a new guitar case, and he was really good too so I have him my spare change.

Some people think they're just scams, but I'd like to think he's gonna actually buy that guitar case (his current one was pretty beat up)