In reply to estivoautumnal:
Even sealed ampules of sterile saline solution has a use-by date. It's physically impossible for anything to happen to that stuff unless the the seal on the packet breaks. Not all use-by dates make sense.
In reality all you need to do is to know what use-by dates are important and what are not. Herbs, spices, salt can be used for every. Vacuum sealed containers can be used well past their use-by date.... the stuff you want to be careful off it just the obvious things like fresh meat, rocket, dairy stuff. I tend to go much more by whether something looks or smells off than by the use-by date. Milk is also a classic for often going off well before its use-by date so I never assume it's OK irrespective of the date on it.