Well maybe we are looking at this the wrong way. People often do charitable things because they like to help other people, so yes, they are receiving self-satisfaction and good feelings from that- but it doesn't mean they aren't selfless. It just means that when they do something selfless they still receive the benefit of feeling good. In my opinion that is still selfless.
However, some of you don't seem to think so since they do receive the benefit of feeling good.
So what about someone that does not like to give things, who hates it in fact. Yet, this person knows it's the right thing to do, and they give money to a charity and they aren't happy about it, they receive nothing in return and they would have rather kept the money for themselves.
I think that person has truly been selfless, they did something they DIDN'T want to do, received NOTHING in return, and helped others. Isn't that the definition of selfless?