I try to only remove the dirt/dust with water. Wiping it with your dirty glove/hand can add to the scratches. Same as your goggles if you where them.

It will be an issue if you ride in a lot of dust. That pic is the worst i have ever seen.

 

..

 

My Foreman had that happen. The sun baked the clearcoat off of it then when any little grain of dirt or sand rubbed on it, whether it be from wind or your glove, it scratched it. I wound up buying a new one from Honda at 20some bucks. Mine is separate from the computer itself.