What is a common consequence of exposing cask ale to air during service?

Exposing cask ale to air during service typically results in rapid oxidation, which can significantly alter the beer's flavor profile. When cask ale is exposed to air, oxygen interacts with the beer and causes it to oxidize more quickly than bottled or kegged beer, which usually has more protection from oxygen during packaging and storage. As the beer oxidizes, it can develop off-flavors such as cardboard, paper, or even sherry-like notes that detract from the intended taste.

While oxidation affects the freshness and overall quality of the beer negatively, it does not improve carbonation, increase flavor intensity, or enhance freshness, making the choice of rapid oxidation the most accurate consequence of exposing cask ale to air during service.