Combine 1/4 cup vinegar with 1/4 cup baking soda. Mix to create a paste-like consistency. If the paste is runny, add a bit more baking soda. If the paste is too thick, add a bit more vinegar. Once the mixture has the consistency of a paste, add 2 to 3 tbsp. water so the mixture is slightly runny, but still mostly paste-like. The mixture should not be liquid.
Dip a carpet-cleaning brush in the mixture. Rub directly onto the carpet stain. Continue scrubbing cleaning paste into the carpet until the stain dissolves.
Dab a damp cloth into the stain to remove the vinegar and baking soda residue. If the baking soda does not lift, allow it to fully dry and then vacuum away.
Liquid Dish Soap
Combine 1 tbsp. liquid dish soap with 2 cups of warm water in a spray bottle.
Spray a liberal amount of solution onto the carpet. Rub into the carpet, using a carpet-cleaning brush. Continue brushing until the stain is removed.
Wipe the spot and remove soap residue, using a damp cloth.
Lay a towel over the carpet and press down to remove any excess water.
Combine 3 oz. of ammonia, 3 oz. of distilled white vinegar, 2 tbsp. of dish detergent and 3 tbsp. of lemon juice with 8 oz. of warm water in a spray bottle. Shake to mix the ingredients.
Spray a liberal amount of mixture directly on the carpet stain. Rub into the carpet with a carpet-cleaning brush. Allow it to work into the carpet for five minutes. Repeat as needed until the stain lifts.
Wipe away any cleaner residue that remains, using a damp cloth.
Lay a towel over the carpet and press down to remove excess water.