Wife's HHR has a typical newer (shoddy) GM steering column that rattles for no sane reason. Juddering front brakes telegraphed through the steering and was driving her nuts. I pulled the rotors. Roughly ground the outer rust ridge/ lip down with a grinding wheel, so it wasn't "sticking up" and going to catch on stuff in my next step. Then I applied a wire cup brush in a 4" angle grinder. Went at it several minutes a side. Let the natural rotation of the grinder move things around. Then I rotated the rotor 90 degrees as my technique may otherwise lead to "high spots". I did notice lines, that could be considered pad outlines, that somewhat, but not fully, were "erased". The first few seconds of "buffing" caused an immediate change/increase in shine, but I kept at it, not feeling satisfied. Put the car back together, 75% better, I'd say. And the price is right. The internet-speak is onto something, "warped rotors" may not always be. Coincidentally, I never felt this in the brake pedal on this car. It was always the steering. Pads and rotors were new a year and a half ago.