Ds2's cot sheets have been in almost constant use for 8 years, and look grimy even fresh out of the cupboard. I know my washing machine and powder work, and that the sheets are clean even if they look rank.
I changed our laundry powder a few years ago to find somehing to which I did not react, and we don't use fabric conditioner.
Going dairy-free cleared up most of the eczema on ds2's face but I can't shift the last bits. It's not bad, just roughness and dryness, but sometimes he complains of sore skin. He often sleeps face down, so I wonder whether it oculd be the sheets...could they be so ingrained that they really are dirty even though they've been washed?