Few things can ruin a shirt quite like underarm stains. Those odorous marks have a way of persisting wash after wash -- and it's not like off-color pits is any kind of style trend. So, instead of cycling your tops through the laundry a ton of times and just hoping it's enough to eliminate your underarm stains, try using this cleaning method from Linda Cobb, Queen of Clean: First, mix the following ingredients into a bowl: 1/2 c.