there is a difference between "best" before and "use by"..
one implies that the quality will degrade after a certain point, the other that you should consume it by a certain date....
just smell it, if it smells off then throw it, regardless of the dates.... which is exactly why we evolved our sense of smell....
oh yea, about botolinium.... puffy cans dont touch.... botolinium is only produced in anaerobic conditions, which is perfect for canned stuff.... so if canned stuff smells funny, throw it away... since botolinium is a neurotoxin, if you eat stuff with it, your lips and toungue will tingle and probably go numb... eat enough of it you stop breathing.... so it's not a good idea....