There are all sorts of dicks out there,
I've had "buyers" who say yes, then decide after a think they don't want it, one even told me he only said yes to give himself thinking time without me selling elsewhere.
I had one who wanted to view a bike I was selling I told him to phone me from the main road & I'd meet him & guide him in, he phoned me an hour late saying he was lost having decided to try & follow his sat nav & got right stroppy when I pointed out that I couldn't direct him without knowing where he was
Best was a guy who came to look at a quad I had on the bay, with a trailer on the back, he'd asked my reserve & I'd told him £700, he then turned up with £700 expecting to buy it, when the bidding was already over £800 , he got quite nasty when I obviously said NO.
Equally I've had plenty of good sales & buys.