It's the same sort of situation in the firearms collector's world. There are so many outright fakes of vintage and collectible guns that even the legitimate stuff is suspect. In the case of the facetious comment I made about Mauser rifles, there is a whole cottage industry dedicated to creating stamping dies for phony proofmarks (called "Waffenampts") and faking collectible guns. I was involved in facilitating the purchase of a real collectible, a pristine example of a rifle issued to the Luftwaffe and virtually unfired, sent home one piece at a time by the uncle of a close friend who was in engineering school with me. All the proofmarks on that one matched, except for the bolt, which is another story by itself. It commanded a very nice price, and both the buyer and the seller came out in good shape.
Jerry