These set-ups are good for general inspection and beauty shots, but they will NOT tell you about wear. Believe me. I did this professionally and you can clean up most well worn tips and they look lovely.
You have to identify the relative size of the area worn flat. Unless a tip is completely worn out you're making a judgment call. You can also see when one side is worn more than the other. Usually, none of this is discernible on a beauty shot.
neo
This is the truth.
I vaguely remember a Shure guide with photos of various degrees of reflected wear-flats ranging from acceptable to worn-out. Anyone have a link to that?