Well, I'm sure about one thing: I wouldn't have had a clue. Not the faintest inkling that anything was wrong.
It might help to see other coins with the same problem. This Pescennius Niger was withdrawn from a major auction when it was pointed out that the edge of the mother coin used to make the copy dies was reproduced on the reverse left side lopping off the tops of the letters when there was plenty of flan left over that should have received those tops. Where sense, Spidey or other, comes in is that you need to be able to explain why those letters are not only missing but cut off so abruptly. Spidey-sense is not something we advertise as a reason people should trust us as a coin authenticator but, when we amateurs trying to learn the subject see something that does not seem quite right, we can listen to Spidey and walk away. I do not envy professionals who are required to rule one way or another on every coin presented to them but we who are just interested in building a collection can say, "No, thanks" and miss out on genuine coins sometimes rather than buying things we will regret. My experience is that coins, however well documented and guaranteed they may be, that I had to be 'convinced' were good never sit right in my head. If one later turns out to be bad, I feel like a grade-A fool. Listen to little birds that whisper in your ear, gut feelings and Spidey-sense even when buying from trusted sources. Coins that make you feel good are better than coins with lingering doubts. I really wish I would learn this lesson. Don't doubt everything just because you don't know but when there is something about a specific coin that bothers you more than usual, buy something else.
Update; FORVM gave me store credit. Not what I asked for and it was very presumptuous of them to assume I didn't want a cash refund, but whatever. I'm in no mood to argue, plus I will return to the hobby with a more focused collection in about a year once I've worked on getting other priorities squared away, so I guess I'll utilize the store credit sooner or later.