It's a pain, I know, but every ride I take in the winter where there is nasty stuff on the roads - I give the scooter a rinse and a bit of a wipe with a pump garden sprayer, The green plastic kind from local hardware store.
Then I use the electric leaf blower to dry it off.
Mask off areas where spray paint is to be applied (heat paint on exhaust, etc.) and give things a squirt.
Stig