Dry-wiping dust off the paint
UAE dust is largely silica, harder than clearcoat, and dragging it with a dry cloth or duster sands the surface. It is the single biggest source of the swirl marks people later pay hundreds of dirhams to polish out. Dust either gets rinsed off with water and lubrication or left alone until it can be.
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.
Judging vendors on the handover shine
Fresh dressing and a wet-look finish flatter any job for 48 hours. The real quality indicators are process questions asked before booking — wash sequence, decontamination steps, depth-gauge use — and how the paint looks under an inspection lamp at handover. Comparing two or three scoped quotes rather than one glossy promise is the cheapest quality control available.