There is some sense to this marketing ploy. Pale lager is still the best selling beer style. This lighter cousin of Pilsner is best served at temperatures approaching freezing. But, that’s only one style. There are many different kinds of beer and, like wine, there’s a different appropriate serving temperature.
Why, you might be asking does this matter? For having a reputation as the drink of the common man, beer is surprising delicate in flavor and aroma. A well balanced beer is a precise mix of sweet, bitter and, sometimes, sour flavors. The right temperature presents these balanced flavors in the way that the brewer intended when she set out to brew the beer. The wrong temperature can accentuate some aspects of the flavor/aroma profile and mask others, creating of the beer nothing like the brewer intended. In order to experience the beer in the way that it was originally intended, it is good to pay attention to the serving temperature guidelines.
There’s a persistent myth among American beer drinkers that British beer is served “warm,” meaning at room temperature. This isn’t the case, in fact, hardly any beer is appropriately served at room temperature. However, many British beers, especially those that fall into the real ale or cask ale category as prescribed by CAMRA, are served at cellar temperatures, at 12-14 C (54-57 F) this is certainly cooler than room temperature. Compared to the coldest beer in town, though, it is quite warm.
So how does one determine the optimal serving temperature for a beer? With the myriad styles now available, it can be a bit overwhelming to try to keep is all straight in your head. A very sloppy rule of thumb would be that ales tend to be best at temperatures on the warmer side and lagers on the cooler side. There are, of course, more precise lists out there that specify serving temperatures for various styles of beer, this one over at RateBeer.com is a good reference. Some brewers are even good enough to make serving temperature suggestions right there on the labels of their beers.
The real answer, though, is what do you like? It’s easy to get lost in the rules with something like this. Wine lovers are often guilty of this, insisting that certain varietals be served only at precise temperatures, in specific glasses and only with certain foods with no room for variation or personal taste. Luckily, the beer world is a bit more forgiving most of the time. So, with an eye to the general guidelines, serve your beer however you and your drinking buddies like it. Do you like ice cold ESB? Then drink it that way. Do you like room temperature Helles? Bottoms up!
The only exception is if you are serving beer in a pub or a restaurant. In that case, customers are going to expect good beer to be served at the generally accepted temperatures. You will have more satisfied customers and, as I pointed out above, these are the temperatures the brewers intended their beers to be served at.
One more point of consideration about beer temperatures is carbonation. Liquid absorbs and holds carbonation better at colder temperatures than warmer ones. So, a very cold beer will remain carbonated longer in a glass or open bottle than a warmer one. This is a secondary concern, really, but something to bear in mind.