Prior to the minimum of 50 posts for the WTB section, a scammer would make 1 seemingly legitimate post. (This is another security action I added, as it prevents 0 post users from sending PM's.) The scammers immediately head to the WTB section. After seeing what people wanted, they would swipe images they found on the internet, and PM them along with prices to users here. I was getting multiple reports each week from forum members to alert me of these scams. Most saying "something doesn't feel right: or, "I found this image from a past Heritage auction. This is a scam" Since the 50 post minimum to view the WTB section, I have not seen 1 report for these types of scams.
The marketplace is different. The offerings take place in an open setting. It also has the security in the form of the community probation and HoS lists. Lots of eyes watching out for scammers. (including me) Whereas the most transactions for the WTB forum are done privately. I could go deeper into this but, I think you get the picture.