The whole direction of where this story is going is misleading, there's not thousands of defaced Leica's out there with the Leica script purposelessly taken off to smuggle them into a country, also a scratched or damaged camera wouldn't bring $$$$ anything on the Black/Grey market, these cameras were individual circumstances of vandalized cameras that's all........
And back in the old days as is now, US servicemen and women ALWAYS run around with more than one camera around their neck, it was the Military members who could afford expensive German and Japanese cameras in the first place, they didn't have to damage their cameras to import them, I had paperwork signed on all my gear before I left Germany and didn't pay a cent in import taxes, (and I came home with more than 6 cameras and at least 10 or 12 lenses).
The Japanese companies added the <EP> Exchange Post symbols to their equipment from 1950 till the early 1970's for Servicemen returning from Asia, together with paperwork, they too didn't have to *deface* their cameras to bring them home.
I think that the amount of "mint condition" or non-defaced smuggled Grey/Black Market cameras from the 1940's and 50's far outweighs a few damaged *defaced* cameras that show up on evilbay, there's no big mystery here............
And on the most part the *defaced* Nazi era cameras and optics were gear that was STAYING in Europe, in the 25+years I've seen *defaced* WW2 Leica's most of them came from Germany/France/Holland where the cameras were still being used, also Leica issued REPLACEMENT top plates for the WW2 era cameras, you can see these marked with the serial numbers starting with nr. instead of the original factory issued no.
Many of the clean original non-defaced WW2 engraved Leica's survived here in the USA where they came home originally as War Trophies.......
Tom