sure ban hammer as it fraud. their some that say they done it and got paid and some that got banned right off the back, i dont advise this. but if you do it i recommend dont do it to a good network you part of. do it to one you dont care about. cause imho the one that get away with it were just lucy enough that they didnt checl their leads.
look at everything they can see, so as you can see it not just simple a ip address. theirs browser id, session id, mac address, your computer name, screen size etc...
http://analyzemy.net/
but me personally i say just dont do it, not worth it.