I spoke to the owner of an auto body shop a few years ago, who told me that he wrote several vehicles off as a total loss or salvage, which becomes permanent on the title.
However, these vehicles were purchased at an auto auction, transferred to another state where some illegal things were done to the title, and the vehicle appeared back here on a used car lot.
I'm not exactly sure how they did it, but people can get stuck with a vehicle that is actually a salvage wreck, and not know it. The vehicle may appear okay, but it's actually not safe to operate.