In which the wine is spoiled, usually oxidized or corked, but that also takes in a host of more geeky flaws like volatile acidity and brett. Technically, there’s a difference between a wine fault and a wine flaw; a fault is a major defect, like oxidation, and the latter is less important, like brett. But both mean the wine is off, and the terms are used interchangeably, even by experts.
The good news is that very little wine, especially compared to 10 and 20 years ago, is flawed. Growing techniques and production methods for almost all of the wine we buy are infinitely better than they were, which means better quality grapes are combined with cleaner, more quality conscious winemaking. Hence it’s very difficult to find a flawed wine on a retail shelf.
The easiest way to detect a flawed wine? If it doesn’t taste or smell the way it’s supposed to. An oxidized wine will taste like bad brandy and a corked wine will smell of wet newspapers or a damp basement. Volatile acidity often smells like a band aid, while brett is like a barnyard.
In this, note the difference between a wine that is flawed and wine that is made poorly or in a style that you don’t like. An example of the latter is high alcohol, which I don’t like but is not a flaw — even though I wish it was. An example of the former are overly-bitter tannins. When we did our tastings at the Cordon Bleu, several of my students insisted that the wine was flawed because the tannins were very harsh. That tannins, by their nature, can be harsh and bitter never seemed to satisfy them, and neither did my explanation that tannin management isn’t a high priority in many cheap red wines.