[paxys]

Simply having a real Facebook account tied to listings and purchases eliminates 99% of them. Both parties can also see when the account was created.

Also everything you list goes through manual approval, so the most obvious spam never makes it through.

[asdff]

It's trivial to make a fake facebook account, and I really doubt most people vet the seller to such lengths. Scams aren't always obvious. I could see how you could generate a fake account, get fake pictures of a fake apartment, and make a fake ad, and not get caught at all.