You don't deserve to be paid because you choose to do something that somebody else may, or may not, want. If you want to be paid for your work, you negotiate that beforehand. Otherwise I would just be walking around talking. Here I am talking now. "You owe me money", right? ... It's up to you whether or not you want to do work with no contract. I think artists do need to do work with no contract, because what we're motivated by is not money. We're motivated by a need to express ourselves and to get our ideas out. That's the motivation. It turns out that when people like it they frequently will support you if you give them a means, but this is not a contract.