If it turns out that Jubal is good the I think the first hypothesis must be right, in which case it will be even tougher for us to find those who are actually scum. At the moment though, there is no way to be sure and so I think Jubal is probably our best lead... Although that foreigner Rob did mention he was the worlds greatest detective or something, maybe he has info?
Anyway, for now I'm going to go ahead and Vote: Jubal.