Garrett
Would rather model the "road warrior" over the museum piece any day. Most of the time a revenue loco was in the yard, out in the elements and probably not wiped down unless it was in for maintenance.
Museum engine do not represent the daily work horse of freight which had to keep a schedule nor does it represent the express that did not have time to set still to be cleaned. A museum engine goes out once in a while on excursion.
Think of it this way, look at the fleet of trucks on the road running daily. I doubt that they are clean or get clean daily when doing a haul across many states or a long interstate run.
That said, all of us are free to choose the era and characteristic of a given engine according to its service.