These cards - in their various guises and ACC numbers/names/categorizations - were used for advertising purposes across a wide variety of product spaces (food, entertainment, clothing etc...) and time - the images were certainly used into the 20's (licensed or otherwise)
As such, they likely went through a variety of steps before they ever made it into distribution, some of which might see the content being generated by an honest-to-goodness print manufacturer using that (licensed?) content for the express purpose of making advertising material in the form of "cards".
For example ...
Back in 1921, Joe Jr (son of the owner of Joe's Auto Body) had a run of advertising material requested, featuring an ad for his Dad's shop on the back of the cards. The ad company ran the "for approval" copies off and gave them to Joe Jr. Dad said we don't have the money for that ... and the advertising campaign died right there, never making it to production. Joe Jr kept the promos, and never considered them "real" because that print run - effectively customer "proofs" - were never acted on, but kept for whatever reason .. Joe Jr - or maybe Joe III sometime later - found them and brought them out.
If they were printed on appropriate equipment at that time, for the express purpose marketing/advertising like other cards of the generation, with licensed images, etc... they're real (to me). If they were printed years later on different printing hardware with different ink, using old images simply as "fantasy" cards, sure, they're fake... I think the empirical evidence says that's not the case.
Maybe some other printer put the time/$$ into a project for reward and it got axed due to use of unlicensed content or some other legalities. Does not change the above statements much, IMO.
I think even the honesty of the guy selling them, but calling them "not real" is sort of moot, if you did not question him as to what he meant by "... they're not real ...", the above example being a case in point... :
- If you asked him, and he said "they were a licensed advertising run we were having made by printing company X for our family's clothing store but grandpa decided not to use it..." would you call it a promo, a proof, or simply "fake"?
- If you asked him and he said "my dad worked at a printing company - we printed them for the advertising company, but their customer decided not to use them ..." dad kept them because he thought they were neat, but we never printed any more... would you call them "promo", "scrap", "fake" ...
- If you asked him and he said "my dad was best friends with an ad/printing company owner and they gave my dad the stuff because they were going to throw it away, but they knew he was into beisbol ... "
- If you asked him and he said "dad lived next door to an advertising company and went through the trash... "
Not having any context except your memory about the conversation and no further details makes this a "he-said" conversation. Not that it is not worthy of discussion, but your insistence on that as the key point as to the fakeness makes me wonder if there is not a middle ground somewhere that is more like reality... one in which the cards - for all intents and purposes - are ones that were licensed and printed for a legit reason and qualify as
real under most definitions, but were considered as "not real" by the holder because he knew that they never saw the light of day for their "intended" purpose.
Yes, there are equally stories on the "fake" side, I'm just trying to make the point that under the circumstances, outcomes from natural events that might explain both: the quality/reality of the cards, and an involved(?) person's contention to the contrary are not at all implausible.