If you were trying to convince someone that the online market places were safer than selling/buying in real life, how would you explain how people have been arrested?
From what I remember people haven't been really caught solely from their use of the site but there were things they did in their offline life which they carelessly linked to their online life/activities.
When I first decided to vend I actually made a notebook documenting known vendor arrests and the things that lead to them. I then made other notes about how to avoid those issues.
One thing struck me though. Most (besides Hero MDPro) were caught by means outside of what vendors commonly prepare for. One big thing amongst others that brought Nod down was his continued use a a specific font utilized across all his stealth combos.
Things like that. I should organize and publish all of it.