The best thing is to let it sit in the sun to bleach out a little bit (not always easy in this time of year, but I hear putting it somewhere like on the dashboard of your car or window sill works as well). I also like oxyclean.
The sun has removed it every time for me. That's how I get the stains out my CDs. I've spent the winter just hanging them on a drying rack and putting them by the sliding glass door, and that has always worked.
Re: BM poop stains?
I try to put a stain remover spray on (Oxy-something is what we have) and soak it as soon as I can....it has worked pretty well.
Breastfeeding Counselor with Breastfeeding USA
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Zout works for me.