Do they salt your roads as well? Here we get sand and salt. My worry is the salt could disolve on a warmer day in melting snow, get trapped under the mask and when it dries, the salt will crystalize, becoming abrasive.
Maybe i should just do it and stop over thinking. My MS3 is the most valuable thing i own at the moment, and my pride and joy (im single, no kids and dont own a house...though it might trump all of those things anyway).
I want to make sure i protect it, but $$ is a factor at the moment
I'm telling you the mask is very tight around the car. Unless you physically went and lifted the mask and poured sand/salt under there and then rubbed all over the mask and forcefully tried to cause damage you aren't going to see any negative effects.
Like I said proper maintenance and care and you'll have no issue. And to answer your original question they salt and sand like crazy.