Yea you can paint rotors, I did mine. You see in his first couple pictures where there is the clean section of rotor, and around the outside of that is a bunch of rust? The clean part is called the fire path. If you paint your rotor, the next time you drive your truck and you hit the brakes, the pads will wear off the paint along the fire path very quickly. Where all the built up rust was will be protected by the paint, and the fire path will be cleaned by the brake pads every time you drive.