Dirt is not patina. As far as fine racing bikes are concearned, proper maintenance should be an ongoing part of the bikes life.

To me this includes cleaning and polishing parts, and replacing tatty bar tape and cables,etc. when needed. I have no problem with a frame showing scratches, faded paint, torn decals, etc. But I'm still going to make sure that frame is free from grime and waxed. I have no problem with alloy cranks showing strap marks and chain scratches, or levers showing a bit of road-rash. But I'm still going to clean and polish those parts, scratches and all. In a nutshell all parts should be made to look as good as they can without altering (re-finishing).

This way a 30-40-50 year old bikes looks its' age but you know everything is tuned, adjusted, safe, quiet, and rideable.

Besides I can't work on a dirty bike. If I'm re-packing hubs, those shells get cleaned inside and out. It might be important to leave oxidation on a Van Erps lamp base not a fine bicycle.