Special Water-Soluble Stains
Try 1 tablespoon of ammonia mixed with 1 cup of water (but not on wool or wool-blend carpet; instead use mild detergent and water). If that doesn't work, you can try one part chlorine bleach to five parts water, but only on solution-dyed carpets, such as polypropylene. Bleach will harm other types of carpets; check with the manufacturer if you are unsure what type of carpet you have.
Cory - A Perfectionists Touch