Shamal season: dust is the enemy of a good finish
On dusty days a careful interior crew will wipe walls down with a damp cloth immediately before cutting in, keep windows shut with the AC filtering the air, and tack-rag any surface that has sat overnight between coats. On exteriors, an honest vendor will simply pause. If a crew is happy to roll a boundary wall while visibility on Sheikh Zayed Road is down to a few hundred metres, that tells you something about the finish you will get.
Dust matters before the first coat too. UAE walls that have gone two or three years without painting carry a fine film of settled dust bonded with humidity, and paint applied straight over it adheres to the dust, not the wall. Proper prep — washing, light sanding, spot-priming patches — is the least glamorous line in a quote and the one most worth paying for.