From my perspective, accounts musn't be involved in any kind of transaction, either selling-buying or being collateral. I think this is a practice that must be stopped in the forum, but, of course, that's just my view.
Regarding the question, well, if you lose your account in a loan, my bet is that the "new owner" will be free of doing whatever he/she feel about the price. As long as selling accounts will be allowed, they can see them as a way of pay-back. I guess that, if selling accounts where absolutely prohibited, then probably they didn't even work as collaterals in a loan.