I was told by "sources close to the dealer in qustion" that the car had had vast amounts of work done by another dealer but that the owner had not allowed the previous dealer to do all the proper repairs to chasis etc. So, whilst it was rotten, it was a very good car mechanically. The dealer who then took it in p/x sold it to w dealers and then bought it back. It was then sold without anything else particular done as a very good car.
Just what I heard, but I did hear it from a top source.