I’ve always found that with imported beers but also domestic craft beers, whether pasteurized or not (craft beers generally are not), bottled or canned, beers within 3 months of packaging offer a surer route to a good experience than an older beer especially one over 6 months old. There are always exceptions, and any beer drunk cold and without much attention to palate will be okay no matter (within reason) how old it is. But those seeking the optimal beer experience are advised in my experience to seek out beers as new as possible off the line, even strong, well-hopped and bottle-conditioned beers.
I am setting aside in these notes the experience of buying beers to lay down, or store. They are separate category but for beers intended for current consumption, it is advisable in my experience to buy and drink them as new as possible.
Some beers that are recently packaged may still offer an unsatisfactory experience. Damp paper oxidation is still a problem occasionally, for craft beers in particular. Other factors can explain this though, too much residual oxygen in the container, poor handling of the beer in bulk before packaging, poor storage or handling at the wholesale level, etc.
In general, craft beers, especially local ones but even from far afield, are more reliable than in the past. This may be because more today are bottle- or can-conditioned. A yeast presence in the beer can scavenge stray oxygen in the container, so can a substance in the interior lining of crown caps frequently used today. Filtered beers are, IMO again, subject to faster degradation than unfiltered ones unless pasteurized. Perhaps too beers with a lot of hops or other flavours can disguise the damp paper or other faults lurking underneath so to speak. A retired brewer from a national brewer once told me that certain kinds of “soft” faults in dark beers are less apparent than in pale beers because dark malts “hide” them better.
It is a mantra that brown glass is more protective than green. Still, even brown glass will let in light over time. Cans of course are exempt from this but they conduct heat (and chill) much more effectively than glass, with commensurate risk for degradation. This is why even pasteurized imports seem superior, or IMO they are, when 2-3 months vs. say, 6-9 months from packaging. Jever cans in our market seem by by the date system currently to be about 10 weeks from canning date, Kovel too. They are drinking very well, with a full natural taste a lot of imported beers seem to lose after a few months in the can or bottle. Pilsner Urquell is the gold standard in Ontario of a very fresh beer showing its stuff. For years now, you can find these – I buy the cans only – at about 10-12 weeks from packaging and they always taste really good.
Most imported beers use a best-by system and a one year freshness window. Urquell cans use a 9 month system: so, factoring out the year, add three months to the date appearing on the base and that is packaging date. Some bottles and cans have more delphic systems, or none at all, and in such cases it is can be harder to know how old the product is. Sometimes you can tell by a change in label design or simply by a spruce appearance of the label.
Finally, some beers of course will never satisfy no matter how new, simply because they aren’t your preferred taste. But all beers should ideally have a level playing field in the market. It offers the surest way to taste them as the brewer intended, and to make comparisons and judgments from there. The market isn’t perfect and never will be, but careful attention to the best-by or other freshness codes on bottles and cans in general will offer a better experience than simply buying willy-nilly.