What these newbies don't know or don't want to know is that all designs on coin dies are exactly the same . Sometimes the die design can be changed a little with a few things like over polishing to remove die damage or maybe die wear. Remember all the dies of a particular coin starts out identical like all the rest of the group.
The open mouth on your dime is from over polishing. After I saw your post I started looking for open mouths in my Kennedy collection. Here are a couple photos of a closed mouth and open mouth from the same die (71D DDO-004/DDR-002), stage A, EDS, and stage C, LDS...defiantly over polishing.
[edited] Well the same coin dealer asks me if I seen another--for whatever reason he likes it and I respect that cause that's his personal decision .Who am I to decide what someone else likes.I believe the hobby is about collecting what you like and not what other people feel you should like
I have not seen this in the Cherrypickers Guide. So I will see if I can prove this one. I know one of the authors of the book.
This is basically like a poor man's '55. Valueless. It only racks about 5 bucks in UNC grades to the right buyer. Not only that, they're 65 years old! Older than my mama. Same hype here with the little value the coin truly has. Maybe one day it'll be sold as a 'open mouth FDR dime" for 5 bucks. Or 20 with inflation. I got a poor man's right here, Cause I keep seeing that "if there aint photos, it ain't real" sentence.
I would do the right thing to maintain a clear conscious.. Go back to the person and be honest. Tell him it is really not worth that much. Obviously this person has absolutely no knowledge of such issues. He would respect you for the truthfulness! Also.. When someone tells you "TAKE THE MONEY" I'm sure they meant it in a joking manner.. I know I did.