The feel of the stock alone isn't going to tell the story. I own a picture from 1941 with a matte, almost card stock like textured finish paper that I know for certain it is genuine and from the era because I got it from the original archiver and it has the original stamps on it. I've also owned various movie stills on a similar textured paper that I could definitely date to the 1920s because they were autographed (and in some cases dated) by the silent film stars depicted and I got them from the estate of the recipient, who was a make-up artist for the movies in the era. Also, there were many publicity photos made by various entities that weren't necessarily on "standard" glossy photo paper; the ones that come to mind most readily are the H815 Adam Hats pieces, which are on a very heavy creamy (now) stock with a matte finish that feel a lot like cards.
