Virgin Islands (U.S.)
The fact of the matter is that "mint" is a subject grading that varies widely depending on who you talk to. Only in the coin world does it have an official definition. One man's opinion a does not a definition make. With all due respect to Mr. Bill Rogers, you are not the ultimate authority on the grading of vintage banjos. Your opinion is just your opinion.
If, "by definition", a used banjo cannot be "mint", then why does the option even exist? I think the OP needs to take his complaints up with the administrator of the website, not the users.
What should happen is the options should be cut down to only include two choices: New and Used. The specific condition can be described within the advertisement itself.
'Tone ring for sale' 1 hr
'Drone notes ?' 2 hrs
'Deportee' 3 hrs
'Auld Lang Syne' 3 hrs
'Even more amazing!' 3 hrs