Alas, it works both ways....
Within an hour of posting my daugher's Sunfish
for sale on Craigslist, I got an email saying "yes, I want it, and I'll pay you $50 extra to hold it and take it off the board till it's picked up.... then the "unfortunately, I'm out of town,so I'll need to send you a check, blah, blah...
Out of courtesy, I sent a reply, stating that we only accepted real cash, so send the check to a relative, and have him/her come look at the boat. Never heard from the "buyer/scammer" again.
Ebay and Craigslist, especially, are places for folks with eyes wide open.
Sher