I've also sold a few via Facebook recently and was surprised by it's reach; seems to get people who aren't on Pinside or looking for games on CL.
You get a ton more responses than you do here but the bullshit ratio is HUGE...expect numerous:
ridiculous lowballs. I mean ridiculous. And usually without a message. I had an ad for a Centaur and got a message from a guy: "500"." Same doofus sent me the same message on a breakshot, I decided to just ban him.
non sequiter PMs from people with zero interest in buying a game: "I think I got a game from you once." "I love that game!" "Hey you are in New york? Cool I am planning on visiting"
"Is X game for sale?" You'll see an increasing number of exasperated sellers on Facebook including "ONLY X game is for sale, not others in picture" though really, good luck with that.
"Why are you selling?"
"Will you sell it for (stupid lowball) and will you cover shipping?"
But I'm not gonna complain I've managed to sell a few games via Facebook. Like I said you'll just be getting a ton of nonsense as well.