DIet soda, if not kept in a coolish area, gets a serious whang to it... Had a guy at the lake got a deal on a truckload, and stuffed it in a conex... It was frickin' gnarsty...
Beat me to it - diet soda doesn't seem to last too long beyond the freshness date. Beer, too, but that usually isn't around long enough to expire.
I've heard of some hideously expensive very old vintage wines seriously disappointing the rich connoisseurs who bought them once they were opened up. ("See, I'm so rich I spent $10k on this wine - have a sip and tell me what you think!"
)
Hmmm . . . I found an unopened box of panko bread crumbs in the back of my pantry with a freshness date of (drum roll please) . . . 2013. Wonder if they're stale.