I scale used keys much like the grade scale used for record collectors...
mint - might as well be from NIB
very good - can tell is used but not much
good - wear, some shine but still good texture, no major scratches, chips etc
fair - useable for everyday not showcasing, mostly shiny little texture, very mild discoloration, light scratches, small chips (like very tiny from cap pulling)
poor - still useable but ugly, mirror shine gloss zero texture, mild scratches, chips moderate discoloration
garbage - self explanatory