The pictures are always part of the description, I am always ready to answer questions. These macro pictures show everything in often brutal way, in natura the models always look (much) better.
MINT : the model is brand new (extremely rare)
NM: near mint, the model is (virtually) flawless, possibly very small errors
A: very good condition, the model can for example have a small paint defect.
B: good condition, may for example have a paint defect or a small crack in the windscreen, etc.
C: fairly playes with / damage / missing parts (these are always explicitly mentioned)
D: poor to very poor condition, heavily damaged and missing parts
It is not easy to make a meaningful scale, but in most cases the pictures tell the story.