One thing you have to understand is,
The orignal owner of the account, CAN always get the account back. The account names cannot be changed. But you're most likely NOT to get scammed by the orignal account owners, it's usually the random people who trade these accounts, they have dozens of x-owners are the ones that are the scammers.
IE: Make sure they're the only person with OWNERSHIP on the account, so theres no "oh my brother" or my "sisters dog" took the account back, it wasnt me!" , those usual lame [censored] excuse.
Only trade with the guy if;
1. He is the orignal account owner, and can prove he is, must be willing to talk on vent,phone and keep in contact for future reference.
2. If the character can be Xfered off the account, make sure you do that ASAP, it's the only way you can have the character you bought/traded safe. If they did end up reclaiming the account, they'd be reclaiming an empty account.
3. Read 1 and 2.
That's about all, but defo stay away from accounts that have had 2+ owners.