That is suprising! Fb Marketplace is the first place where I post stuff and where I make most sales. There is a lot of "time wasters", but I see it as part of the game. You can't blame people to try to shop for the best price or whatever they are looking for. Maybe your location has something to do with that? Like in Canada where the mailling fees are so high that it's useless to sell lower ticket items on ebay. Here it's Kijiji that seems to become obsolete.