I think an even patina looks nice. However, when using my 66's with black powder (which is every time) at Cowboy shoots, I return home with some nasty hard dark deposits on top of the receiver. When I started this 25 years ago I was concerned about possible pitting under that mess. I guess that is an unfounded concern as I have never heard anyone complain about it. However, I developed a habit of at least a moderate polishing to clean that gunk. Old habits die hard so I continue to use Flitz.