I haven't sold anything online for years, but back when I'd try to sell something on Craigslist this was exactly the kind of thing I would get.
And if it wasn't them, it was the serial hagglers.
I could be selling a brand new porche for $1 and I'd get someone trying to negotiate down to $0.90
One dude agreed to buy something, then told me I had to drive 2 hours to sell it to him because he was 4 hours away. It was a $50 item
Edit: it was weird that about half the time when someone would agree to buy something they'd stop replying or just send back "don't need it" or something.
My best story and I think it's long lost to time is I tried to transfer a lease on a car. Had some dude tell me he would pay the lease but I could keep the car under my name and insurance. No amount of back and forth was explaining to him why that was utterly insane for me to do.