Keep in mind that not all stains can be removed. Bleached areas, whether caused by sunlight or liquid bleach, cannot really be addressed. Some companies can re-dye those sections, but don't count on a perfect color match. Urine, if allowed to dry, may also leave a permanent stain. Stains from foods that have a lot of food coloring, such as Kool Aid, mustard, or grape soda, are often impossible to remove. The only chance you have of avoiding a permanent stain with these colored food items is to act very quickly when the spill occurs. Many stains containing sugar attract dirt so effectively that if the attracted dirt is similar in color to the carpet, the underlying stain is completely hidden until cleaning. Then, with all the camouflaging dirt removed, the underlying stain becomes obvious and appears to be "new."