"Why? Everything in them until you open them is sterilized. It might reduce the nutritional value a little or effect the taste, but it won't spoil."

O.K. Some of you physicians or biologists out there correct my impression that botulism, even in canned foods thought to be properly canned and sterilized, is a risk often forwarned by swollen cans. If so, how do you tell if the swollen can is from heat alone, or Clostridium botulinum growth?