You apologize about as much as Konsi.
It’s fine, we love you.

I clean the scanner regularly, it’s just surprisingly hard to clean it 100%

The trick I think is finding a good solvent for your media.
Coloured pencil would be mostly waxes and oils.
My go-to is usually a high % isopropyl alcohol, it cleans up pretty well, dries fast (you don’t want leftover solvent touching your next scan). Next up, if it’s really persistent would be odorless mineral spirits. (Odorful?) mineral spirits work too I guess, but given the choice I much pretty prefer the odorless stuff.

I very much prefer kimwipes over paper towels which usually are a bit too scratchy and can leave some fluff behind. Microfiber cloths are reusable, but once you load the fibers with waxes, it doesn’t really work as well.

Do check that your scanner top is glass and not cheap plastic before using mineral spirits.
As with anything, try it out in an inconspicuous spot first to be sure.

Otherwise, isn’t Scan without trace is a third level spell available to trickery domain clerics?