Thanks Alan,
I think that summary is a good overview of how I feel about the topic as I know you do too and hence why you bang on about the Rally Car identities. I also couldn't help but think of Big Sam and it's previous life as a "thinner" (PZR style body) and it's rebirth as another car later down the track etc..
This gave me a good chuckle. Having seen this multiple times on various forums and places like BAT.
This is what I thought of in particular when I saw the auction that started this discussion. As mentioned I've seen the sale of Spirit R plates for an FD3S being offered in a similar vein, although it would be very hard to fake such a car (I'm sure many try) given the chassis no. is checkable against a Mazda database. Along with all the unique parts for that model, but I've seen a rather craft individual here in Australia attempt to rebirth an AU market FD (which all had sunroof's like the UK spec cars) as a Spirit R and no late model FDs had sunroof's... Go figure. Like I mentioned above, a true enthusiast will usually be able to spot the fakes (given enough time to examine the details) but the less educated individual may find themselves with something that isn't as it was described.