Just to add on what Yahoo62278 said, others could just be scammers claiming to have an account for sale yet they actually don't. They afe just waiting prey on anyone stupid enough to trust them.
I think no one uses this method to cheat, it's not optimal
Everyone knows that buying an account will involve a lot of security, they won't be stupid to lose money, the escrow is always chosen for safe.
Not only on this forum, bitcointalk accounts are always available out there, intermediary trading sites. If I remember correctly, I have seen a few people selling accounts on bitify. They are expensive and have no information