In my Mean Green Cleaning post, I listed 3% hydrogen peroxide as a strong (but gentle) stain remover for the off chance that the all purpose cleaner did not fully work. This post is dedicated to the power of peroxide. (Mouse over the pics for a description.)
***** DISCLAIMER: ALWAYS test peroxide in an inconspicuous area first. You may also have to “rinse” the area with a little water (use a squirt bottle) after using the peroxide. And last but not least, DO NOT douse your carpet (with any liquid). For me, the trick to this working is to use a very light sprinkling or misting of peroxide and repeat the process as needed (rather than saturating the carpet). I’m not sure, but I would think that saturating the carpet could damage the fibers and the pad.