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.
I wish I seen this profile earlier... Gave me an alpha key and then deleted me after. But its fine because I'm revoking the key I gave him so \o/
Edit: Now he has given me negative rep. Well done man, I don't even trade really so it doesn't effect me! But now I am a beta tester this week and I have my key back :D
Attempted to pass off a beta key of war hammer 40,000. Removed me as friend, blocked and ignored on barter when confronted. Not very wise as I didn't come off rude or offensive in any way and even offered a bit of advice to avoid any real trouble with other traders. Judging from previous complaints this is not the first time.
-rep, gave me an alpha test key which doesn't give me a permanent game. Started offering me "free keys" for other games I had.