Account dealing on bitcointalk promotes scamming, because you can buy an account with green trust and the victim would have no idea that the current owner of the account wasn't the one who earned the trust.

Account sales also encourage spam, because  knuckleheads who can't write English buy accounts to get into sig campaigns. 

And so on.  So there are a number of us who feel strongly that it's untrustworthy behavior and leave feedback accordingly.