A wine fault or defect is an unpleasant characteristic of a wine often resulting from poor winemaking practices or storage conditions, and leading to wine spoilage. Many of the compounds that cause wine faults are already naturally present in wine but at insufficient concentrations to adversely affect it. In fact, depending on perception, these concentrations may impart positive characters to the wine. However when the concentration of these compounds greatly exceeds the sensory threshold, they replace or obscure the flavors and aromas that the wine should be expressing. Ultimately the quality of the wine is reduced, making it less appealing and sometimes undrinkable.

Weinfehler ist eine Sammelbezeichnung für unerwünschte Geschmacks-, Geruchs- oder optische Eindrücke im Wein. Eine wichtige Aufgabe der Sensorik ist es, solche Qualitätsmängel festzustellen und zu beschreiben.

A borhibákat könnyebb megelozni, mint javítani, mert a helytelenül kezelt bor, már soha nem lesz jó, csak esetleg iható.