On my Magic Keyboard for the 2018 iPP, I have a skin only on the bottom of the keyboard, as it's the side that seems to get scuffed the most.I have the Smart Keyboard Folio, 3rd gen, and the underside that sits on whatever surface you’re using the device on developed a couple roughened areas. And I only used it propped on a pillow or a smooth topped lap desk. Looking at YouTube reviews of these keyboards I saw that almost all of the ones that were shown in the reviews had the same roughened areas. So that’s inevitable, the Magic Keyboard is made of the same material so I’ve got them now covered in skins also. Which makes the color you order irrelevant most of it won’t be visible, at least externally. The material of the keyboards feels really nice but is not durable. Fingerprints are easy to deal with, those roughened areas can’t be resolved. I’ve wondered that if those areas get even worse do they just wear down to the structure underneath. I preferred not to find out and ordered the skins. On the old keyboard I just have the underside covered, on the new one I covered all of the outside surfaces, I haven’t messed with any of the interior surfaces.
The keyboard itself I just wipe down before using it, but I don't obsess. Black or white, the case will get scuffs, bits of discoloration, it's just inevitable from use. I just maintain it as I use it and don't worry about it.