One of my parents cars had damage to the paint from egg, but that's cause it was on there for up to a week in the sun, we were on holidays when it was done. However if you get it off in the next day or two I've never had a problem. Egg shells on the other are real pain. My mates car got egged one night in a quiet residential street and you can see where the eggs hit cause there's tiny little chips down to the metal in the shape of the egg.