Distance selling is fraught with dangers on both sides.
As a buyer: Pay with Paypal gift and you might never see the goods you paid for, and won't see your money back. Pay with bank transfer, and the same applies. If goods do turn up and they're damaged then you get stuck with the argument that "It was fine when I sent it!", or the silent treatment.
As a seller: Someone pays with Paypal with fees paid, and you send the goods. The buyer receives the goods and raises a Paypal claim for his money back using any of the possible "excuses" and Paypal side with the buyer for a partial refund or whatever. Or the case is won for a full refund and the buyer sends back a different item which they've exchanged for the good one they got through the post.
Or the other clever one is to buy something and pay for it with Paypal with fees paid, then agree to go and collect. Once collected the buyer claims that the goods haven't been sent, the seller can't provide tracking details or proof of posting, and Paypal give the buyer their money back.
By far and away the best way to buy and sell is to meet face to face and pay cash.
Having a forum section with an up to date list of scammers and bad sellers/buyers won't stop the bad people stealing from the stupid people.