There's a fair amount of caution built into expiration dates. Food makers must account for close to the worst-case-scenario when setting those dates. That's why many items are perfectly edible at the time of their expiration date. And almost all foods remain good at their "sell-by" date, because it's an indication aimed at grocers, not us.
As you've probably experienced, there are many date labels, all with slightly different meanings. "Best-by" is less severe than "use-by" or "good until." But keep in mind that because most dates indicate quality, not food safety.
Trust your senses above all else. What you see, smell and maybe even taste should tell you all that you need to know. For more tips visit my website, American Wasteland.