Once your home’s exterior has been professionally cleaned there is no need to rub the finish

Resist the urge to rub your fingers across the siding like you’re checking a hotel room for dust. Exterior paint isn’t a countertop, and rubbing it can disturb oxidized (chalky) paint. Admire it with your eyes, not your fingertips.

In the before and after images above my customer rubbed away the protective top layer of their weathered paint, exposing the underlying base layers and accumulated grime. The “black” smudges are a mixture of this chalky residue and trapped dirt under the oxidized layer of paint.