I buy a lot of stuff from Craigslist locally. Usually only from ads where they list a name and a phone number. You can usually tell from the ad whether they are flakey on not. I've sold quite a few things too. Common to get "Do you still have it?" emails. These are web bots just looking for valid email addresses. Don't even bother to reply. I sell my old tires, hay and some farm equipment. Latest big ticket items have been 1/2 of a windmill fan for decorating to the gals who watch Home & Garden TV. Half the fan brings more that the fan, motor and tail vane. Some buyers just want someone to talk to. They reply with an email describing their daily calender entries for the next month as if I give a crap. Had a few who asked a question about an item come by a week later and are mad as **** because I sold it a week ago. (I told you I might be interested in it !")
In buying, I use searchtempest.com to look around the state for cool stuff. I also just search for items spelled wrong. Bought a VERY nice Peter Wright "anvel" for $200 well worth 2-3 times that on the open market when I fix the spelling error. I stay away from ads listing latters, traylors and hydrolick stuff.
WORST buyers have been people looking for horse hay. Never show, no money, brought car instead of truck or trailer, insulted when I insist on cash money, can't count out 25 bales, can't load a pickup bed with more than 11 without directions from Google, return moldy bales that are a different twine color than I sell (as in they're not from me, lady).
Now we sell a lot of large industrial types of items (factory and old barn lights, wire baskets, work benches, other decorator things) we buy at estate sales. "Industrial Look" is hot right now. These buyers don't care what it costs, they just WANT it. So I give in and sell it to them at my asking price.
I'm gonna sell my 1960's juke box soon with 10 pictures and can't wait to tangle with the crowd likely to ask: "does it play DVDs?", "Blue Tooth enabled"? "wireless?", "can you deliver to the South Pole?" "will it fit in my Prius?" "What color is it ?" You get the idea. Still fun to tangle with them. Life is tough. Its tougher if you're stupid....