I understand....
All one really needs to do is look at there Join date and the number of posts they have. That will tell you how new they are and I could ho up 50 posts in about 3 minutes. I know based on the laws in my state (or at least the way I understand them), I have to either buy from someone in state or use an FFL to get the gun to my state. Some simple questions would let me know what the seller knows and doesn't know about buying and selling weapons.
Common Sense really does rule on any forum you are on. You either trust the guy without question or.... you don't.
Would I buy off a forum, car part, truck part, gun or gun parts, probably not. However, if Tactical Advantage had a laser sight for sale because he is in the same location as me, I would probably be interested and try to swing a deal. For the same gear and the guy lives two states away, I wouldn't even give it a thought.
We can put as much criteria as we want to prevent scams, people will still fall prey to these idiots, I see it happen on the truck forums