What I have known since childhood is that dairy products have a "sell by" date - and are supposed to be good for a week after that date.

Eggs, I ignore the date on the carton, and give them the float test. You can tell how fresh an egg is easily - fill a bowl or pan with water, place the egg in it. If it lays down, it is nice and fresh. If it stands straight up, it is very stale, may be used only for baking if flavor isn't an issue. If one end tilts up a bit, it is okay, just means it is somewhere in between. If it floats, discard!