Use a spray bottle full of vinegar to lightly spray the area, then wipe it with a cloth. For deeper stains, saturate the area with vinegar or carpet cleaner, sprinkle with baking soda, and vacuum the area once the baking soda has dried. Don’t attempt to scrub stains away from carpets.
Vacuum thoroughly, and then mix one part hot water with one part hot white vinegar and 1 tsp (good like in Wisk) laundry detergent and put that into the tank of a rental steam cleaner.
The vinegar might be effective in a HD carpet cleaning machine, but if not. White vinegar is a very mild acid, and IS quite useful in a variety of .
No matter how clean you keep your home, old carpets accumulate stains and appear dingy. Regular cleaning brightens the carpet and removes the stains.
Dip a white cloth into the detergent solution and use it to sponge the really dirty areas of your carpet. This will help to lift the dirt from the carpet to the cloth.