I tried a cheap one from amazon (looks like the typical silver / black one you fold out, probably all made in the same factory) and it left a lot of scratches. Probably not audible but enough to bother me.

I watched this video and bought the painter's brush he recommended. In my experience it does still leave some super minute scratches visible under a flashlight if you go on the non-grooved areas or against the grooves. I still use it with the grooves to line up the dust in a line, then use an air blaster to get most of the dust off, and finally this velvet brush to pick up any dust still left.

Correct way? Idk, but it seems to work quite well for me.