This type of activity is either an indication that someone is a scammer, or it isn't. There really is not a lot of gritty area here.
I disagree. Would a now Staff member who sold accounts be more or less trustworthy than some random who was selling accounts? Negative trust means that you do not trust the person, not necessarily that they scammed someone.
Despite Blazed's "untrustworthy" actions (I personally believe that account sales do not warrant a negative trust), I would certainly trust him with all my coins.