Well this weekend I dyed a dozen or so slips, nightgowns, peignoir robes etc with acid dyes - good for nylon as well as silk and wool (I did a sweater and scarf too).  This time I really paid attention to mixing and stirring and got better results, not so many streaks.  Also, a boiling scour before dyeing is not a bad idea when it comes to used lingerie - some stains are just invisible until the dye finds them.