I disagree to say that it's never rude to ask. I think anytime you ask for something that you know will make the other person uncomfortable, it's rude.
My brother-in-law is very proud of saying that he never asks anyone for money, they just send it to him of their own accord. True, but this usually follows a 1/2 hour converation with him where he details that he can't pay the light bill, can't buy groceries, etc. Until the other party finally says "How bout if I send you $50?"
Agreed, the other party should grow a spine, but his elderly parents have a hard time doing so.