If you remove the black matte finish of a Glock, what remains is a graphite-colored shiny gray finish, reminiscent of scribbling a pencil on paper.
It's an attractive, subdued, two tone finish. I owned a pistol like this once, and it was fairly unique.
I liked it.
If you like this type of finish, then more power to you. Shouldn't hurt the gun.
Just don't polish THROUGH the tenifer.
S