A nice '68 Torino 390 HiPo GT sold to the kid down the street very cheap - they weren't worth much at 7-8 years old. Told him that it had a "bad" carb and shifter linkage and that needed rebuilding. He haunted me until I did the rebuilds as a freebie just to shut him up (plus his brother was "one of those kind of local cops" and had a 'little mans complex as well'").

A '76 F250/460ci "California" engine - advertised it and a local guy bought it. Came back a month or so later and said it had a rattle and when he took it apart he said it a rod installed with a bend plus backwards. This was an engine that had never been apart. He haunted me for a while, but finally gave up. He drove it up until 2 years ago and offered it back to me about 18mos ago as a freeie, but still running, but totally rotted.

Other then a couple of instances where I had to 'eat' some repairs, never a really bad deal