It looks as if we each have our own ideas about how to keep the paint perfect. A brush shouldn’t hold grit, the grit should fall out, unless of course that truck had some sort of glue like substance on it, like pitch or tar. It’s the bristles that I think might be a problem, they start off with very soft ends but with use those ends wear leaving the coarser “stem” parts of the bristles.
I think diapers and microfiber are probably equivalent, before we had microfiber it was soft cloths for all of us. As far as soaps go, there’s the gentle soap that breaks the surface tension of the water allowing it to lift the dirt, then there are the powerful detergents that dissolve and remove the wax. They each have their place but for general washing I want something that simply wets the car and loosens the dirt.
A water wash sounds good, the ideal is a distilled or deionized water rinse, so no spots. If plain tap water is used, the evaporting water will leave deposits of whatever is in the water. Calcium or other divalent ionic salts are likely to be unsightly and abrasive left behind after the water has evaporated. So is one better off leaving the tiny spots or soaking them up with a soft diaper wipe? I vote for the diaper. Microfiber is the best of both worlds, that is until you get into discussions of the edge bindings, those are not microfiber so they can be of concern for tiny scratches.
The bottom line is that some of our paint will make it 5-10 years with nary a scratch and some us will have paint that will get weathered, not just from washing but from blowing sand and dust that hits at 60-70 mph as we drive. We try to keep it factory fresh but driving takes its toll. Driving, overhead birds, trucks picking up small stones, construction zones, road tar, acid rain, pine tree sap, it never ends.
As long as one has a preferred way to clean the car and the cleaning doesn’t add to the daily paint stressors, then it’s a good thing. Some of us add films that protect the paint. Most of us use surface protecting treatments, things that covrer or bond to clearcoat, and shed rain. Even then some waxes such as carnubas will eventually harden and form micro abrasive particles.
For me, it’s a pressure washer, gentle car wash covering the car in foam from a foam cannon, a careful rinse, and an electric yard blower to blow off most of the water, then a microfiber cloth to soak up the very tiny residual droplets. Any fine dirt that’s not removed gets a spray of waterless car cleaner and a microfiber wipe, done with a rolling technique so only fresh microfiber touches the paint.
Any of you that show this much concern could wash my car. I’d be happy knowing It’d be in excellent hands.