A fifth generation tape that has only been through Nakamichi decks will likely sound better than a third generation tape that has gone through cheap dubbers. Grading The main thing to remember is be honest and consistent. If you grade tapes high just to attract people, they won't ever trade with you again. Grading is very subjective and varies from person to person. It is a good idea to thoroughly explain your grading philosophy on your list.
Most people use letter grades.
Some try to grade all tapes on the same scale, some make allowances for older tapes and AUD tapes and grade them easier. I try to grade everything on the same scale. Either way, explain your approach on your list. Only low gen SBD or FM qualify. A A very good clear tape with no major problems.