Do your darker clothes have perspiration stain marks on them? To remove them add 1 part vinegar to 4 parts water, soak offending garment for half an hour and then either wash or rinse as usual - the stains magically disappear!
Removing Nicotine Stains on Clothing
Cleaning Underarm Stains on White T-shirts
Cleaning Yellow Stains on White T-Shirts
Lightening the Look of Dark Wooden Cabinets
Blue Stains Showing Up on Washed Clothing
Changing Hair Color from Dark to Light