Some of the premium beers will sit for weeks before rotating the stock. Micro breweries usually have fresh stuff, but, their recipes can be so exotic as to the point of distraction. The top selling beer by a huge margin is Bud Lite.
I would rather have a 6 month old Newcastle than several "fresh" micros I can think of. Most of the high end import beers have some sort of preservative in them that will allow them to stay stable for much longer periods of time. Many micros also use live yeast, or at least employer lower standards of filtering that can lead to pretty quick deterioration of the product. Couple that with generally lower QC standards and much less stringent shelf life policies, and you are much more likely to get bad quality micro than you are to get a bad quality import or large domestic.
You'd be surprised at what many brewers/suppliers do not want you to know about code dates. There is a reason most are encrypted to keep the average consumer from actually knowing how old the beer is, or how close it is to expiration.
Just for a point of clarification, Bud Light is the largest selling beer in the U.S., but not by a "huge margin" (obviously it depends on the definition of "huge"). Budweiser is still the world's largest selling beer.
