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.
Pressure-washing the engine bay at home
Water driven past connector seals into coils, the alternator or fuse boxes causes faults that surface days later as corrosion develops, which is why the damage rarely gets connected to the wash. Bays need degreaser, brushes, covered electronics and low pressure or steam — a job for someone who has done it a few hundred times.
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.