I've had similar experience. I usually get a few of these for each ad, though I haven't had any of the "What's your PayPal address?" offers, just guys who say thay want it, and don't respond further. I believe many of the zero fb folks you refer to are just trolling though and may not realize how inconsiderate they are being, maybe simply don't care.
I've come to the conclusion that until I have money, or have become convinced that the money is in the mail and the person is committed, and playing in good faith, then tried keep my options open by telling them the first person with cash gets the unit.
I've come to the conclusion that until I have money, or have become convinced that the money is in the mail and the person is committed, and playing in good faith, then tried keep my options open by telling them the first person with cash gets the unit.