Different sellers have different standards and interpretations of the grades like "excellent" and "very good" etc. So opinions will differ. Personally I would say your guitar is "very good", which IMO is kind of like a B- on a report card. Not the greatest, but pretty decent all things considered.
But the best way to go about it is to avoid those terms that can be so easily misinterpreted, and just stick to the facts. Describe each ding and scratch accurately, saying things like "there is a patch about 1" square on the back upper bout where the finish has scraped through down to the wood, but the wood itself is undamaged" or "there is a chip about the size of a pencil tip out of the wood near the neck pocket". Pay a lot of attention to the straightness of the neck and any wear around it.
Once you've done that, you can feel free to talk up how great it sounds, how smooth it plays, and what a rare collectible it is.
