His M.O. is almost always the same, with slight variations. He gathers beta keys and offers them as full operating final game keys, knowing they are not. He also offers stolen keys that get invalidated or revoked afterwards.
If you confront him, he will use one of his canned English sentences "giveaway code sorry" or "i not problem" (meaning it's not his problem) or "company credit card cancel" (yeah, go figure).
All known profiles to date, as well as history of his scams to me and to other traders can be found here.
He's gone so far as to attempt to impersonate me and other traders to disguise his actions.
Traded me a Post Human W.A.R. key that was revoked by Steam pretty quickly. Looks like I'm not the only one.
After about a month, something interesting popped up in their tradable list, but when I asked about it to make up for the revokal, they went silent for three days now (see here).
+rep very fast trader, good trade!
He provided a Post Human WAR Key for the BETA only. Now Steam revoked the game from my library. I'm not the only one in this case