My worst example on BC was selling an early 70s Jazz last year to a German based BCer. I held the bass for a month (over Christmas) as he insisted he wanted to fly over and pick it up in person and tickets to London were cheaper in January.
As the relevant Saturday in January approached, he asked me for a list of places (bass shops, record shops) to visit which I did some research on and duly sent to him. I set aside the Saturday to meet him (which meant missing a family activity) and waited for confirmation of his landing at Heathrow. Several hours later, wondering whats going on, I text and say that I hope his flight was good and I look forward to meeting him. He eventually replies and says he missed the flight. I offer (again) to post in secure box etc and he says he will get back to me. A day or two later he says I may as well put bass up FS again as he isn't sure when he could get over to London.
No idea if his story regarding flights booked/missed was true or pure fantasy but I lost a great chunk of a precious Saturday hanging around, held the bass (which was worth close to £2k) for over a month for him, and got no apology.