Well this type of issue can be addressed by the forum modators I think threads that has such content like sell of anything to the forum community and gets lock should be delete to prevent people from still picking interest in it
That's pretty bad too because you lose proof of the scam. I know that the forum doesn't moderate scams, but they should probably make exceptions for cases as blatant as this, or at least prevent manual locking of threads in the marketplace section. This way, someone could at least leave warning messages for people who don't know how the trust system works.
But yeah, it's sad how people are falling for such blatant schemes in the first place. If they're naive enough to fall for something like this, I don't think there's anything anyone can do to protect them.