After some thought, and reading the replies, it could just simply be enough to encourage wise choises. If you intend on buying from a forum user, check their post count. Read their thread involvement. If these few things don’t seem to add up, simply be careful moving forward and ask a lot of questions. As a seller, I don’t think it’s a hassle to have to explain yourself a bit to a person who might be skeptical.
Awareness and logic by potential buyers should be common sense in these days.