Have you seen the Grade & Conditions definitions developed by CCA (previously CC and GTCC). Here's the definitions chart from 20+ years ago, but it still works today. It may not cover every situation, but it's pretty comprehensive, IMO.

If it ain't broke, don't fix it.

https://ccgtcc.com/documents/1101/Official-CC-amp-GTCC-Grade-and-Condition-Descriptions