When I detail an interior, I "play the drums" on the carpeting. I will pound the carpet area with the palms of my hands and watch the sand and dirt come to the surface, where it can be vacummed easily. I will also use a brush to help bring any sand and dirt left in the carpet (especially under the pedals) up to be vacuumed. I then a spray bottle with carpet shampoo solution and lightly mist the carpet area, brush it if it's matted down and then I use my extractor on it. The carpeting comes clean. I save a "sample" from the extractor to show the client what was in the carpeting...sometimes they are amazed!