Matt, I hope your going to read all of these replies to your suggestion. I'm not sure how you would prove who is or isn't a paid anything.
But, in the meantime, you could make it like a software licence to use iHub. You could have a private home license that would be the same as it is now. Then you could have a more expensive commercial license which would cover people who post here as a business, aka paid pumpers or IRP's.
Obviously, that would be based on the honor system and I doubt many would be honest about it. But, it would at least start some sort of infastructure for disclosure and accountability.
Instead of pirated software, they would be pirated posters. Once that is in place, then you could start nailing down some means to prove and catch those who are paid to play and don't disclose it and they could be held in violation of licensing.