McPhat could have someone design "Wash-O-Matic" installer that gave the end-user a choice of wear and dirt.  The interface would be a big dial with six different settings, just like on my washing machine.  ;D

Well, if any airplanes should be dirty, they are Captain Sim's.  It goes along with the interior.  But I don't care either way, honestly.  It is going to be the best, no matter what.