This brings up an interesting question I have wrestled with for awhile. Not all P-51s look like that. Some look a lot smoother and are of more uniform color.
Is this due to photo quality (i.e. details not being captured due to film type, distance, sharpness, or lighting)? Airframe time? Weather exposure?
The effect is undeniably good. I just wonder what takes some airplanes to that point and not others (if photos can be taken at face value).