This is an issue if you are buying an account. You don't know how many times it has been banned, and if any other account of the seller, whether it is still in the seller's hands or sold gets banned then yours get banned too. Even worse, your main accounts then can get caught in it.

Conversely, if you bought an account and spammed with you the seller is in trouble. There is no way of knowing if the account was actually sold or faked.

Best thing to do, make your own account and contribute.