How do you handle account bans? If someone buys your account and gets banned, then all the accounts get compromised as there is no way to know for sure that the account was really sold.
I have sold accounts in the past where the buyer immediately started making dozens of spammy posts, and was quickly banned. None of my other accounts were affected. I think it is pretty fair to say that BadBear is pretty good at detecting when an account was sold.
I had that question following this thread
https://bitcointalk.org/index.php?topic=994097.0IMO banning everyone, seller, buyer is the right thing to do as one can never be sure that the account has indeed been sold. You would obviously disagree to this, but not doing this creates a loophole.
It shouldn't be too difficult to tell if an account is sold, especially if the posting habits changes substantially. It is also not difficult to tell when an account is sold, especially considering the fact that most people who are going to get banned for signature spam are not going to go out of their way to hide the fact that their account is banned.
Edit: the fact that I have a reputation of putting in a lot of effort into what I post likely is going to give me additional credibility when it comes to these decisions.
Also if you are curious, yes people have likely tried to get me banned by buying multiple accounts and then immediately started posting large amounts of shit posts in a very short amount of time. I was notified by the person that purchased them that they were banned for 14 days within an hour (they had probably made ~150 one liners in that time) and no none of my other accounts that I own were affected.