There's a difference between sig whores, and good posters who rent their sig space out for a fair fee. I'm all for stripping sigs of the post count whores with nothing to say, but there should be no problem having useful posters making some money/giving a company exposure. I don't think there really is a solution, but I believe companies will only pay those who can get them the right exposure for the right amount of money. There really doesn't need to be a crackdown. The real whores won't be selling their sigs a few months from now. Only a select few will be able to make some cash.
