So I have done a number of print jobs and sold a few things on the forum (as I am sure many others have). I have also nearly been scammed, and I know others actually have been scammed from deals that originate via a thread on in the B/S/T (buy/sell/trade) sections. I realize that the forum operators are not liable for anything what so ever.
That said, why not have a "User Feedback" forum?
Each user can start a thread for their feedback from the deals they conduct on the forums. Other users can post their feedback with pictures, reviews, and a link to the respective thread that the deal originated from.
Obviously it would need to operate on somewhat of an honors system, but it seems like it would be a good way for users to judge another users reputation and what not.
greghoge.com
HUGE 3D PRINTER PARTS SALE!!!