Being Swindled Isn't Fun

I always hate and feel terrible when a homeless person approaches me. It's a difficult situation, knowing if they really are homeless, or just trying to rip you off. One time, I was going to my car and this man who said he just needed five dollars for gas approached me. I gave it to him, not really thinking about it. A few days later, I saw him do the same exact thing to someone else. I was so angry; I went over to them and told the lady not to give him any money because it was a scam. The swindler was angry, but he didn't say anything. I've been wary ever since.