Foul-smelling stools are usually associated with what you eat, but may be a sign of a medical condition.
Stools normally have an unpleasant odor, but one that is recognized as fairly common. Stools that have an extremely bad, out-of-the-ordinary odor may be associated with certain medical conditions. Foul-smelling stools also have normal causes, most notably diet.
Foul-smelling stools may occur in conjunction with floating stools.