What is needed is a Committee of individuals appointed by Pinside, these would include a Pricing Expert, Condition Inspector, and Hacking Detective. Together these people would determine if the listing is legit, the price within narrow perimeters, and condition acceptable based on Committee standards. Otherwise the listing will be removed and the Member suspended indefinitely.
This will limit/eliminate spurious, speculative ads by shady people. Only the largest Contributors would be selected for Committee, which they would have to serve on for 6 Months or lose their Membership.