Why is removing stuck rings with dental floss painless for some people?

My left and right hands have different sensitivities from playing guitar all my life. Auto body work also forces a person to dial in touch at a very atypical level, especially for a painter like myself. I've trained a few apprentices and even those with an initially poor sense of touch eventually dial in the skill. There is a level of imperfections in the final finishing steps where it is impossible to see the issue in oblique view due to the matte finish of primer/sealers. This is well after blocking and guide coats are no longer helpful. At this stage, there are still many imperfections that will create obvious errors after clear coat because the distorted reflections that may be present in the final gloss. These errors can be very color dependant. They can manifest in the way metallics settle within the color coat making the issue visible here as well. The worst color for reflective errors is black. With some whites a painter can get away with nearly any minor error at this stage without consequences as long as there is enough orange peel present in the factory finish.

Anyway, there are two tricks to finding late stage errors in the primer. The easy way is to use a wax and grease remover solvent wiped liberally across the panel. This will temporarily create a clear coat like gloss that will show exactly what the final reflective properties will be like after clear is applied. This is always the final test before you shoot anything. However, doing this a whole bunch of times just because you can't feel the issues is very amateur noob territory. Any skilled painter learns how to touch a panel in a sweeping feel using the center pad of each finger tip and sliding a hand along the surface in a way that one can feel even the most subtle of errors. I can feel the reflection–no joke.

A painter spends a ton of time wet sanding by hand too. This leads to sanding off most of the outer skin on your hands. In fact, when I was really busy and working 12-14 hour days, I had to quit when my fingers started to bleed. They actually bleed the pattern of your fingerprints when you sand through them with a fine grit over time. The thin skin and heat sensitivity it creates helps to dial in the skill.

That is my long bla bla bla about why, in my experience, anyone can dial in their sensitivity and awareness as a skill. When I worked on heavy equipment or in the machine shop, I had tough callused hands; with auto body thin soft and sensitive, and after all my crashes and battles with cars on a bicycle, like a seriously scared up brawler.