I was stupid enough to fall for the "Pay me the shipping and I'll send it to you and you can pay for the item when you get it". I lost €20 to that scam. Never again. I have completely stopped trusting anyone really. I rarely buy used things anymore due to all the possible problems. I bought a bike a year ago for my son. It looked great but after a week, the problems started showing. Basically, it was trash. If I were to replace everything that was wrong with it, it would cost me the same as a new one so I got a new one.Glad it worked out. So many scams on FB Marketplace - esp in vehicles that I've noted. Never bought anything on it, so best to take extra caution in future.
If any red flags show up - best to walk away - even if a great deal.
I currently paraphrase Rick Harrison from Pawn Stars: "It's not that I don't trust you, I don't trust anyone".
FB Marketplace is FULL of scammers. If you want used goods, try eBay, at least they have the buyer protection. I have gotten my money back on occasion for faulty goods.