If the insurance company haven't repaired the vehicle they would have paid out on it and then probably recouped some of the money by selling the vehicle at a salvage auction.
This is were the problems start. It could have been bought then by anybody, most likely by a dealer who would have sold it as a accident repairable.
I'm not sure if accident repairables have to undergo safety checks like an sva test, but they didn't a few years back.
Its all about how good a repair has been done, personally imho I wouldn't touch a car like this without having details about the repair, but like I say thats just my opinion.
oatcake