Buying a ceramic coating without paint correction underneath
A coating is transparent and permanent enough to be annoying: it seals in every swirl and etch mark beneath it. The suspiciously cheap coating deals almost always skip decontamination and polishing, which is precisely where the labour cost lives. Pay for the prep or skip the coating.
Washing or detailing on sun-heated panels
Products behave differently at 70 degrees: soap flash-dries into streaks, polish gums up, coatings cure before they level, and cold water on hot glass and paint adds thermal shock. Morning slots, shade or basement parking are not comfort preferences — they change the quality of the result.
Polishing too often
Every machine polish removes clearcoat, and clearcoat is a finite budget of roughly 40–60 microns for the car's whole life. Cars that get 'a quick buff' at every service end up with thin, UV-vulnerable paint within a few years. Protect more, polish less: correction should be an occasional reset, not routine maintenance.