I wonder if publicly admitting these sketchy dealings is at all a factor in the disqualification/blacklisting process. Probably harder for EK sales since there's no link between GH username and transaction. But at least for 4Grabs, CC does need GH usernames in those emails..
It sometimes seems to me like he's allowing it to happen, if he sees a user sell a marked up CC (whether by a little or by a lot) in the classifieds but still lets them buy caps during his 4Grabs sales.
Yeah, sure, it could be that the seller had bought it for a high cost, but that person still contributed to the problem by originally purchasing it at that high cost.
And yeah, there are private sales (like not via classifieds listings, but by PM/email/in-person/eBay).. I don't have a response to that one.