For the truly NOS razors you have no worries. But I have seen a few where they were billed as NOS "Mint" but a close inspection of the photos revealed rust, pitting, uneven wear. While its rare that any of the current vendors seem to lie about a razor, they almost all state "see pictures for condition" so you MUST look closely. use the zoom function when ever possible. Don't be afraid to write them asking for more pictures, and Do Research!
Seriously, I cant count how many Puma 6/8 I have seen that look great, until you compare it to a photo of a mint one, and see how the toe has been ground down to soften the point, or has been worn down to 5/8 Same for many of the Friodurs. a 17 should be about 7/8 not 6/8 !!! Research people, RESEARCH!