Wine is a living medium and unfortunately can develop unwanted and unpleasant colors, flavors, and aromas. Wine reacts to its surrounding environment and contains many different microorganisms. Winemakers must be proactive to prevent spoilage and to retain quality. Even so, conditions will occasionally allow an undesired microbe to take hold and spoil the wine.

Some of the major flaws are: Brettanomyces/Dekkera, Oxidation, Hydrogen Sulfide, Mercaptans, and Volatile Acidity.