If you follow the TUG guidelines for verifying a rental, it is just about impossible to get scammed - because you verify your reservation with the resort or resort management company.
The big advantage when you rent from an owner is that you can save as much as 50%. However, renting privately is not for everyone. Some people would rather pay more, for the security of renting directly from the resort, and that's your prerogative.
On a few occasions I have had renters who were so suspicious and nervous, that I declined to rent to them, because it just wasn't worth the hassle. Recently I had an attorney who wanted to rent an inexpensive rental from me, but he wanted to re-write my rental agreement using his terms. I said, "Look, no offense but I'm only making $150 on this rental and it's just not worth my time and effort to change my rental process for one renter, so I'm going to respectfully decline your offer."
Once, I had a mom who didn't want to give me her home address for the reservation, because she didn't want to, "put her children at risk." That was a strange one.
Renting privately takes trust on both sides, and if you are not comfortable with it, I don't think you should do it.