There is no numbered scale in everyday use here, so the honest listing is a short list said in the same order every time.
The five headings
Corners and edges — wear, rubbing, exposed material, any repair. Hardware — plating loss, tarnish, scratches, whether the zip runs and the clasp holds. Lining and interior — tears, pen marks, stains, loose threads, anything left behind. Shape — does it stand unpropped, or has storage changed it? Smell — storage, smoke, damp, perfume. Say it.
Anything that is not in those five is a bonus. Anything missing from them is a question a buyer will ask, or worse, will not ask and will find.
Useful words
New with tags — unused, tags present. New without tags — unused, no tags. Excellent — used lightly, no corner wear worth the name. Good — used, with wear you have described. Worn — real wear, priced for it.
Say the word and then say the faults. The word alone means too many things to too many people.
Repairs and refinishing
Resewn seams, replaced zips, re-edged corners, recoloured leather — all normal, all to be declared. Recolouring especially, because it changes how the bag ages and a buyer deserves to know.
Say the smell
It is the one thing in this list that cannot be photographed, which is exactly why it must be written. A bag that smells and says so is a bag sold at the right price. A bag that smells and does not say so is a return.
Questions people ask
What if I cannot tell whether a mark will clean off?
Describe it as it is now. Never describe a condition you hope the buyer will reach.
Is "vintage" a condition?
No, it is an age. Give the condition separately.
How honest is too honest?
There is no such thing in this category. Naming the flaw raises the price.