Boy we haven't had this discussion in quite a while. Used to be we talked about this everyday. I believe out of date items are not as evident as say 5 years ago and certainly not as 10 years ago. I always look out of habit but things are much, much better than they used to be. I don't believe there is as much "repackaging" as we use to hear about either.
I'm with Diane, most items that are over by a few months are fine but again common sense. Pasta, milk, cereal and such I leave behind.
Also if you want to make a complaint in a store you should seek out someone with authority to remedy your complaint and an ordinary employee is usually not that avenue, especially here in Belize. If that employee acted without direction they could be looking for a new job.