LOL the stain never goes away with an partially digested sock either...
The stain came out, the unfortunate part was that it was the same color as the carpet, thus the not finding it for several days. It was in a corner on the other side of the entertainment center.
Have you tried oxygen bleach or Spot Shot? Those two products are pretty good for laundry, and the latter is actually for carpet. We have ceramic tile floors because of ease of cleaning. (Carpet has so much surface area that having it would be like living in a Petri dish.)