Yup, I find sometimes things look poo stained but then after the next wash/sunning they come good again. I'm not bothered by a bit of staining on a clean nappy though, (given it's likely just to get pooed on again, LOL!) so I haven't experimented much. I have used vinegar in the wash on the odd occasion, but this is supposed to wear out the elastic, so I don't do it often. (Only when we've had HEAPS of rain and they haven't been out in the sun for ages. They tend to get a bit stinky when dried inside all the time too, so I use a couple of drops of eucalyptus at the same time.)