Too right, add to that the real life efffect of abrasive salt, sun fade and areas being repainted at different times with what were probably different batches of 'Grey'.
I reckon that #1 is the varnished one, #2 is the original while #3 is the match.
Great debates have been had on the correct shade of Olive Drab and German 'Dunkelgelb' in Military modelling circles, but in the end the same issues apply added to that is weathering and you have a movable feast. Objects further away also look lighter and with less brilliance so scale effect has relevence.
Judges be darned, build it how you want it and accept that like all artists, we are our own critics, but you have to let a project alone at some point or you will never move on to your next project.