Let's set a few things straight.
Everyone encounters "spoiled food" - food you are handling that has outlived its "best before" date. You may very well be throwing away perfectly good food. Every short while, this issue is raised in our store. One of our customers made a good point about "best before" dates and we thought we'd try and clarify a few things for everybody. Read through this somewhat dated (2011), but very insightful and relevant article.
Web MD puts it concisely - Best if used by (or before)" date. This refers strictly to quality, not safety. This date is recommended for best flavor or quality. It is not a purchase or safety date. Sour cream, for instance, is already sour, but can have a zippier, fresh taste when freshly sour (if that's not an oxymoron!)
If you're wondering the best way to safely and surely consume "expired" goods, this utility is a lifesaver!