Beer certainly is an odd one! Some (craft) craft beers will age gracefully -- improving, even -- for years. Industrial lagers... not so much.
I scored once with an imported (Belgian) craft beer at the local supermarket, heavily marked down price because the sell-by date was approaching. Some days later, marked down by half again because the date had passed. Needless to say, I bought all I could carry.
This is a tricky one, because at some point you need to think about the integrity of the product's packaging, and how well it's been stored.
Craft beer *in a can* will not age gracefully. Even in a bottle, while it will probably be fine, how much light exposure are the bottle getting, have they been left out in the sun at any point etc.
Best before dates, hard expiry dates (if required), and ideally including a packaged on date would be a pretty ideal amount of information.
It depends on the beer type as well. Malty strong beers age well. Hoppy beers don't because the compounds are volatile. Malty beers benefit in flavor from continued breakdown of their chemical compounds, hoppy beers don't.
> Malty strong beers age well. Hoppy beers don't because the compounds are volatile.
> IPA's always taste off to me.
That sounds contradictory to what I've heard about IPAs: that they were created because the normal beers the British had at the time wouldn't survive the journey to India, so they added a lot more hops and called it India Pale Ale. Based on that, I'd expect them to age better, not worse, than other kinds, but I'm not a beer person and this is just secondhand knowledge that I've never bothered to verify.
The amount of hops in the beers from that story were about as bitter as a common blonde ale.
The modern IPA is nothing like that anymore. Also its the aroma compounds of hops that breaks down so fast, not the bittering aspects.This is why you can store a Russian imperial stout (high hop bitterness, low hop aroma, very high abv) but not normally a double/triple IPA (high hop bitterness, high hop aroma, high abv) and defiantly not age a normal IPA or session IPA (high hop aroma, low abv).
*Some overly malty double and triple IPAs will age into a nice barley wine if given enough time.
The hops are somewhat antibacterial, so they can help against contamination, but the hop flavors break down over time, and light and oxidation are what "skunk" a beer.
"Craft beer in a can will not age gracefully. Even in a bottle, while it will probably be fine, how much light exposure are the bottle getting, have they been left out in the sun at any point etc."
A modern beer can, on a newer canning line, is superior to a bottle in every single way. This debate about bottles being better than cans is from years ago. Cans and especially the canning machines have come a very long way in the last 15 years. That is one of the many reasons why almost every brewery is slowly switching to cans.
In regard to aging beers, there are a many important factors. The biggest enemy in aging a beer is oxygen. Oxygen gives beer a cardboard, paper flavor or a very raisin-y flavor, eventually it makes the entire beer taste like soy sauce.
As you mentioned zero light in a can so no skunking, although brown bottles stored in a dark cool place don't experience much of this. But clear, green and other bottles do. Bottle caps slowly leak oxygen in over a very long time and is why you might see a oxygen absorbing material in the under side of some bottle caps.
On the flip side one majorly common way a can will go bad in aging is from a seal alignment issue. This is especially common in smaller breweries as automated seam inspectors are quite expensive. The seal will visually look great. But if you tear it apart and measure the folds its quite common for them to be a little bit off, which can slowly leak out carbonation and in oxygen.
I scored once with an imported (Belgian) craft beer at the local supermarket, heavily marked down price because the sell-by date was approaching. Some days later, marked down by half again because the date had passed. Needless to say, I bought all I could carry.