Carpets may look clean on the surface, but underneath the fibers can be countless of small particles. Dirt, dust, sand, dead skin cells, pet dander, etc. accumulate on your floor coverings every day. If they are not removed, germs can grow and multiply, triggering coughs, flu and other illnesses. Another thing that can make your carpets look dirty are stains, and they can be difficult to get rid of and require a little bit of elbow grease.