I too understand this.....
Which is why most of my cars aren't sold on.....
They're scrapped!!
Which is no loss, as most of my last cars were already on their last legs. But I have 'sold' a car a while back, well more swapped really. It was a MK3 Astra Sport swapped for a MK3 Astra CDX in better nick.
The lad I done the deal with, just thrashed it with no mercy and then cut up with a sthil saw. But the body had more hits than Michael Jackson, clutch was shagged and the engine ticked cold or warm and dropped a cylinder for fun.