What's the deal with all these absolutely mint Heuer Bunds? I know parts were swapped around when they were serviced by the military etc, but there are so many absolutely mint looking Bunds that one can't help but ask the question 'how so?'

And for the propose of full disclosure, I own one of these 'mint bunds' - perfect case, perfect dial, strong lume'. I doubt these bunds age any better than any other Heuer or were taken better care of en masse than any other tool watch of their vintage, so what's the deal?