Old Ale
BJCP 17b
Strength and character varies widely. The predominant defining quality for this style is the impression of age, which can manifest itself in different ways (complexity, lactic, Brett, oxidation, leather, vinous qualities, etc.). Even if these qualities are otherwise faults, if the resulting character of the beer is still pleasantly drinkable and complex, then those characteristics are acceptable. In no way should those allowable characteristics be interpreted as making an undrinkably off beer as somehow in style.