Quote:
if an unknown variety or error is mentioned usually it gets a response of its not listed so it can't be
I honestly don't remember that answer coming up. Unlisted things get posted every once in a while and usually referred to a way to submit them for listing. Considerably harder right now with the CONECA change and Wexler really backed up with submissions, but things that look good and unlisted aren't dismissed as "can't be".
Some of us generally just don't regularly post unlisted stuff as it is less educational. Without a listing it is just less informative and quite frankly most of the unlisted coins are really quite minor.
Here is an example. I found this 1935 minor unlisted
DDO a week or two ago. Most visible on the BE of LIBERTY and a bit on the tail of the 9. But not sure it would help anyone out by posting it, as it's just some minor doubling that has gone un-noticed to this point.

So if you have a coin you think might be a variety or error, even if unlisted, you should get honest opinions here on whether folks think it is a variety or error unlisted or not. But to assist with this, generally unlisted things need to be on a pretty decent coin without a lot of damage and very clearly photographed. Good luck with your searching!