"I'm fully aware that there were some problems in the past and thus the unfortunate need to keep moderator involvement on them. I guess these private swaps could be a viable option, but wouldn't it also be possible for the host to collect the flies and vanish?"
Only know of this twice; and 'he's' now an Internet topic of ... for a lack of a better term ... 'conversation.' I'll leave at that, save for his log in picture has the word "Banned" across his face. IP shut down, as that will do a lot of good. Just go to a public library and re-up under a different name?
Only thing that 'work,' is the words. 6'ish posts and you've got him nailed.