May be infection. Infection, particularly bacterial vaginosis, is the most common cause of foul-smelling vaginal discharge. Normal discharge is clear or white, and may have a slight odor but usually doesn't smell. Poor hygiene, as in other parts of the body, can be a culprit too-it's best to wash the external area w/ mild soap and water during your shower, and never douche! if the smell bothers you, see your dr.