Out of the 6 or so transactions I conducted when buying/selling accounts, only 1 was stolen back.

I let it go, but months later I initiated a password reset out of sheer curiosity and it was sent to my address. Converted their accounts to my own bnet account.

I was also able to find the person's twitter account and read their posts, found out their car had been stolen recently. Ah, karma is a bitch.