You are right, it is odd.......but strictly a matter of personal taste.....so you must either give the customer what he wants or turn down the job.......probably in his mind he is "keeping it original" by not refinishing the other parts.....so be it....
The 'patina' that cannot be removed with lacquer thinner or other petroleum based cleaners, i.e. after the grime and dirt and oil is gone, is generally surface rust, no matter how smooth it has become from handling, it is rust (an oxide)....on the other hand, the discoloration from faded case colors is not rust....
