imo you gotta factor in a lot of stuff 
  
- join date 
- activity  
- their off-site activities (if they can't be found anywhere else it's kinda worrying) 
- the nature of their posts, how they act 
- do they act like a 10 year old on the forums 
- feedback 
- nature of the feedback, is it small trades etc 
  
apart from account recoveries i don't really get how people can still get scammed, using a MM is so easy and judging someone's character is quite easy too :p