If I can afford it, and I feel that it's needed, I can help out. However, if I feel they're simply just trying to take advantage of me, then I'd just back off. Sometimes, saying no can just basically open up a can of worms that I'd prefer to leave closed.
It's even more annoying when you need help and ask for it, but people refuse to believe that you're broke enough to ask for help. It's always frustrating...