What characteristic is common in a drain pour?

A drain pour refers to a beer that is so unpleasant to taste that the drinker chooses to pour it down the drain instead of finishing it. This typically occurs due to the presence of off-flavors, which can result from various factors, including flaws in the brewing process, contamination, improper storage, or expired ingredients. These undesirable flavors can range from being overly sour or oxidized to exhibiting inappropriate aromas or tastes like diacetyl (buttery flavor), skunky (light-struck flavor), or excessive bitterness.

In contrast, high alcohol levels, pleasant aftertastes, or rich mouthfeels may be characteristics of certain beer styles but do not contribute to the decision to dispose of a beer. A drain pour signifies dissatisfaction based on the experience of off-flavors, making this the defining characteristic of the situation.