Let me start by defining the difference between a spot and a stain: a spot is any foreign material (soil, liquid, etc.) that is removable by standard cleaning methods.(The foreign material is on or around the carpet fiber) A stain is a foreign material (soil, liquid, etc.) on the carpet that is not usually removable by standard cleaning methods. (The foreign material has penetrated soaked into fiber and has changed or damaged the fiber itself). Some stains may be very difficult or impossible to remove. If we cant remove that stain, then it may not be possible to remove it.