Can a car cover scratch paint or cause damage?

It can. A cover placed on a dirty car can grind dust into the paint when it moves in the wind, and a cover that does not breathe can trap moisture against the surface. Use a cover only on a clean car, choose one that fits snugly and is designed for the environment, indoor or outdoor, and keep the inside of the cover clean. In windy outdoor conditions, a poorly fitted cover can do more harm than good.