I hear some folks are painting them shiny black to make them look as attractive as DA rotors at significantly less cost. Maybe try using high temp engine spray paint? My question is how will the paint react with the high temperatures in braking.
You could use automotive brake caliper paint, and go black, red, yellow, whatever color. Typically good to 800-950F, should be way more than enough for a bike rotor. Often comes in a can for brushing rather than a spray can, so no worry about overspray. Whether it’s worth the material cost and time vs just buying a set of DA rotors though… shrug
Actual brake cleaner is highly toxic. Unless you’re dealing with contamination I’d stick with alcohol and a clean rag or paper towel, start at the outside and wipe towards the inside to avoid dragging any contam to the braking surface.
Funny you should bring this up. Yesterday after my ride I decided to do a general cleaning since I had the bike up on the stand to swap chains. I normally don’t clean the rotors but noticed they were a little grimy so I just wetted a rag with 91% rubbing alcohol and wiped down the mat surfaces. It seemed to remove all of the grime and as a bonus you can clean the braking surface if you happen to touch the rotors.