According to yesterday's Wall Street Journal:
A loaf of bread has it. So does a carton of milk. But if you're looking for the expiration date on a bottle of beer, forget about it -- for many brewers, that information is a closely guarded secret.
There are now more bottles of beer on the store wall than ever -- more than 2,000 domestic brands alone -- making it harder for both stores and consumers to steer clear of the stale stuff. Age is critical: Nearly all beer begins to deteriorate before it even leaves the plant, partly due to oxygen in the bottle, and many experts say most brews are well past their prime after six months.
To identify when bottles and cans need to be yanked from the shelves, many brewers imprint them with cryptic letters and numbers that distributors can translate. The trouble is they look more like hieroglyphics to beer drinkers, and most makers don't decipher them for consumers.
So, the editors embarked upon a beer aging odyssey, to reveal the meaning behing the hieroglyphics. Check out their "Cracking the Beer Codes" cheat sheet.
This is all well and good, but I do have to raise my hand about the whole investigation. Why the heck did they choose beers like Pabst Blue Ribbon, Miller Genuine Draft, Molson, Labatt Blue, etc? Does the "old" factor really apply to these bottom of the barrel brews? Let's face facts, if you drink PBR on a regular basis, you're not looking for a flavorful experience - just a drunk one.