My opinion is that airplanes have a life like everything else,from factory fresh to the junk yard and everything in between.Some were maintained better than others.Some had strictly military lives and others went on to be civilian.There is no right or wrong way to weather an aircraft.Just have fun with it and it can be very rewarding.How about a diorama of a dirty aircraft being cleaned then you can have it both ways.As long as you dont show exhaust streaks on the wingtips anything goes as far as I am concerned.Cheers! John.