The carpet and Rug Institute recommends using Seal of Approval carpet cleaning products. But when you don't have an approval product on hand or you have tough spots and stains, here are some useful tips.
With blood you should rinse quickly with cool water. Follow with an approved cleaning solution or a mixture of 1/4 teaspoon clear (no bleach, no lanolin) dish washing liquid with one cup cool water. Blot and dry quickly.
Dye and food stains such as beverages, medicines, cosmetics, foods, and other liquids containing dyes, should be absorbed first. Then try the liquid dish washing solution described in the blood remedy. Blot, repeat, and rinse with clear water on a clean, white towel or a white paper towel. Dry. Depending on the substance involved, it may require professional cleaning.
Fingernail polish can be removed using a non-acetone fingernail polish removal. Apply a small amount of remover on a white cloth and work it in from the edges of the spill to the center. Blot the area using lukewarm tap water. Dry with a clean cloth.
Ink (ballpoint pen) comes off with rubbing alcohol (70 percent isopropyl) applied to a cloth or paper towel. Don't pour rubbing alcohol directly on the spot.
Paint (latex) responds to the detergent solution described in the blood remedy. Blot, repeat, and dry. Other types of paint such as enamel or oil require other responses.
For pet urine try a solution of one part white vinegar and one part water.