I've also been scammed and had the account recalled from under me. I unfortunately didn't have all the information. I didn't have the last name of the person that opened the account, but even if I had the name I couldn't know the credit card number used to activate the account. In other words it is impossible to have "all" the information on the account.
The next time I was successful in buying an account. Of course, I insisted on getting the sellers full name, address and phone number as well as the account info includeng secret question and emailaddress used on the account. Of course if the OO really wanted to get the account back, they have the credit card used to verify the account when it was first opened. So I negotiated with the seller to sign a clear statement that he was selling his account, for how much, and agree to never contact Blizzard about the account.
The seller was legit and had no issue signing the document. I don't belive the document was legally binding since he couldn't legally sell the account in the first place, but it could be used to prove to Blizzard that the account was sold and not hacked. Unfortunatly the only thing a buyer can do with it is get the account banned.
The bottom line is you can be scammed. You can make it clear that if it is recalled, the account will get banned but a scammer probably won't care. The OO might care since he (or she) put all the effort into building the character. Therefore, as others have said, make sure you know the seller. Make sure he/she has reputation and verify that person you are dealing with is the same person as the one with the reputation.
Good luck.
p.s. This is the agreement I used last time:
“I, <seller full name>, the seller, agree to provide <buyer full name>, the buyer, the user name and password to the World Of Warcraft account under <the name the account is under> containing the following characters <Character1> and <character2> on <server> hereafter called the account. Upon receipt of payment in the amount of $<amount> from the buyer, I agree to never attempt to change the password on the account, to provide the secret question and answer for the account, to forward any emails sent to me from Blizzard regarding the account to <buyeremail> and to assist the buyer to make certain the account is transferred to his control. Further I agree that once I have received payment I will not contact Blizzard concerning the account unless authorized to do so by the buyer. Finally I agree that if I am ever contacted by Blizzard regarding the account I will forward any emails or letters to the buyer.”
