I'm not against your suggestion, but I think that we need to clean up board that realky matters first. I haven't checked, but from what I know almost all (or maybe all) Bitcoin paying campaign aren't paying for posts in off-topic. Though, I don't know how about bounties. If majority of bounties are paying for posts in it, then disabling signatures sounds not bad. But I'm a afraid that it won't solve problem in general - plague just will spread to other parts of forum.