Granted I haven't cammed on MFC in a while, but there were a few members who I definitely remember banning repeatedly (lifetime ban + ignore) and they were still able to come back within a few days.
One particular guy always had his usernames as serial killers, always one account, would change the username here and there though. He would tip though but be rude to me/other members which is how I knew it was the same account because of the tip history. I don't know how he was able to gain access again after each time he was banned, again, I'd always click on lifetime ban and ignore.
Anyway, someone suggested that some higher paying members have been able to request being unbanned from a model's room. I have absolutely no idea how true that is or not, but who knows, maybe it's possible that they play innocent to support. The frequency of his username changes definitely suggest that he's spent enough to have over 10K points. Anyway, after messaging support about the bans and explaining why I'd repeatedly banned him, I did not see him in my chatroom again. It's possible it was a glitch, but the whole thing was weird.