Those vertical black stripes down the face of your gutters are not really dirt. They are bonded oxidation and road film, which is why they survive every rainstorm and every attempt to hose them off. Brightening uses a dedicated cleaner applied by hand along the gutter face, and you get a white gutter line back instead of a striped one. It runs $75 to $175 depending on the length of the run and the height. It is a finishing touch that makes a house wash look considerably better, so most people add it on.
