If the buyer does this, he will have a big problem, as it is very easy to take the account back with this info. I fell for this trick once!
I bought an account and got all the needed infos (email access, secret answers and last gold purchases.
The account got taken back 3 months after the purchase, as I was too stupid to change the account's name!
Support told me "well, you have already requested to change the e-mail of this char as you have been hacked - why asking to change it again?"
it was a PAIN!
So, beware.
When buying an account:
First thing after gaining access: changing credentials and putting the char on PRIVATE on RealmEye!
After that change the name of it as you desire.
Else you will just be ripped-off like happened on me!
PS: The seller just created this account to sell this. Be careful