The clearcoat on the stainless version's aluminum frame tends to show carry wear, and rather quickly, in my estimation. The stainless parts get holster polished, and the clearcoat gets edge wear, and peels. Some of them look like they have leprosy. Mine is beyond that in most areas (just bare aluminum now, IOW), but on the left side over the S&W seal, the clearcoat is cracked just like it did in other areas, but because of where it is, it is ... brown, a bit, from dirt and sweat and grime sitting in those minute finish flaws. I think my next project on this gun is to remove all of the clearcoat.
But none of that really matters on a gun made of stainless and aluminum, since there's still no corrosion going on. I can leave it the way it is, and let the finish continue to wear away, and nothing bad is actually going to happen to the gun. If I had a 442 with as much finish wear as this 642 has, there would be some serious risk of corrosion (rust) to the barrel and cylinder.