Dented cans ok I have eaten to many and would argue that in extreme cases you would get this piercing that would start the chain reaction of bacteria growing in the can.
(Although I know it is stated that a dented "can" should be looked on as dangerous, as with any of our preps common sense must be in place, so know the other signs to look for.)
You know some jars have them little depressed circle things on the lids and if raised discard the jar, this is due to mostly botulism breeding inside the jar and this would force the jar lid to pop up, it has kind of the same effect on cans the base and top can swell, this is something to look for also smell/look and I guess last of all taste.
We should try best avoiding dented cans for long-term stores as a rule.
http://www.monkeysee.com/play/7762-how-t...e-gone-bad