Honestly if I see no wear I usually put down a little strip of a stealth protector in high wear areas like scoops from pinball pal. I bet if you contacted them they would even do custom sized strips if needed. I usually just cut them in size that I need. Hard to notice and very easy to remove with no glue (no mess) if you want to take em off. For HUO machine I think that would provide enough protection to prevent wear.

I just realized my previous post did not really pertain to your questions sorry about that. Well I don't think they will detract from it's value as they are removable. Unless they left marks after they are removed. One reason it may raise red flags is because some people wrongfully use them to cover up an already damaged area which is not the right way to go about it. If there is a problem it should be fixed then put on the protector because as Cliffy said they are protectors not cover ups. As some mentioned above take before and after pics and that should let any buyer see straight up that you are not covering up damage.

Hahaa, WOW...