Rotating nozzles are great for certain tough jobs. They work well for blasting off peeling paint for one. Basically they are a zero degree nozzle that spins at extreme speed allowing the user to cover a large area. A zero degree nozzle is the most powerful stream a pressure washer can make. It doesn't fan out much. The downside is that they do not cover much area. Try cleaning a sidewalk with a stream the size of a pencil. A rotating nozzle changes that pencil size stream to a cone shape several inches wide. Home Depot has one for 3000psi washers for $35.