There's a great difference between weathering and dirt.
My first tour in SEA was almost at the end of the 'Hun's' operational stint and the few I had the good luck to get a look at were worn but never neglected.
If you feel the need for some weathered subjects that is fine but strike a balance between clean aircraft and operational wear and tear, crew chiefs were fussy about their charges and never allowed them to become dirty.
I'll use the appearance of our 'Tracks' in RL and the plastic modelling fraternity's efforts as a comparison.