Years ago, before I ever traveled overseas, I remember hearing that English people drink warm beer. This sounded disgusting, of course, because the only "warm" beer I had ever tasted was the dregs of a cup of Miller or Budweiser from a college keg party that I had drunk too slowly. A few years later I spent some time in the United Kingdom, where I discovered, lo and behold, that their pubs were not devoid of refrigeration. In fact, beers were served at various temperatures according to what type they were. If you ordered a lager, it came chilled, but if you ordered an ale, it was only cool. Some brews were served at room temperature, but never what I would actually call warm.
Americans, including me, have become far more beer-savvy in the last two decades since the explosion of microbreweries has introduced varieties beyond mass-produced—and often nearly flavorless—lager. But the Brits-drink-warm-beer myth (or, more accurately, the all-beer-should-be-ice cold myth) seems to have survived, as President Obama's June exchange with British Prime Minister David Cameron (which I saw on The Daily Show) reminded me. At the G-20 meeting in Canada, Obama and Cameron exchanged beers from their respective countries, and Obama joked that Cameron should drink the Goose Island 312 wheat beer cold. Cameron retorted that Obama could drink his gift, Hobgoblin, cold but that he probably wouldn't like it.
A dark ale or stout served ice cold just doesn't taste as flavorful as it does at a slightly higher temperature. The reason for this is the same as why white wines are usually served chilled, while red wines aren't. Put simply, the volatile compounds associated with certain flavors or odors can be activated or deactivated through heating or cooling. If a flavor is desirable, it needs to be served at a temperature high enough to be detected; conversely, an undesirable flavor can sometimes be suppressed through chilling. So, if you over-chill a beer or wine that is meant to be served cool or at room temperature, you could be killing its complexity.
A chart at Wine.com gives general guidelines for the ideal serving temperatures for different kinds of wines. It explains that a red wine served too warm will taste more alcoholic and even vinegary, too cold and the bite of the tannic acid will overwhelm the other flavors. White wines need to be chilled enough to avoid tasting overly alcoholic and "flabby" but not so much that they lose flavor altogether.
A similar chart for beer, at RealBeer.com, recommends wheat beers and lagers be served at 45 to 50 degrees Fahrenheit (which, incidentally, is still warmer than where most people keep their home refrigerators) and dark ales, including porters and stouts, at 55 to 60 degrees.
Alcoholic beverages aren't the only things that taste best at particular temperatures. Some foods, especially fruits, can lose their flavor if refrigerated. Tomatoes are one of the examples cited most often—refrigeration turns off the enzyme system that helps produce fresh tomato aroma and flavor.
Of course, taste is subjective. If you ask for your red wine on the rocks you might give the sommelier a heart attack—but you're the one who has to drink it.