I know a friend that had an OF for a month or so to help with some big bills. We weren't super close so it wasn't like that weird. I subsribed for a month to her out and got a PPV video, we talked about it beforehand. Was kinda cool, though she wasn't super hot.
I have a buddy though that actually manages some girl's OF account. I can't remember her name but she lives in CA. He said he does it on the side and it covers his rent pretty much (not sure what the split is). He has to respond to a lot of dudes' pics though which is kind of funny.