Some useful guidance on how to find fault with wine

It's one of life's most lamentable tragedies: sometimes, wine goes bad. Like any natural product, it’s vulnerable to flaws, yet many casual drinkers—and even seasoned winos—might not realise when their glass of vino is less than perfect.

Imagine giving someone curdled milk for their coffee or a pot of rancid yoghurt. They’d reel and never let you forget it! So why do we often accept spoiled wine without question?

Part of the issue lies in confidence. The wine world can feel elitist, making many of us hesitant to speak up when we suspect something’s off. To help you spot the most common flaws, here’s a guide to five issues that can ruin your wine — and how to handle them.

Oxidation is a familiar process. Think about what happens when you leave a sliced apple on the counter—it turns brown. The same thing happens to wine when exposed to too much oxygen, causing it to lose its freshness and vibrancy.

While a small amount of oxygen can enhance wine, too much makes it flat and unpleasant. Oxidised white wine takes on a murky, amber hue, while reds turn a dull brown. It smells like cider vinegar or cheap sherry, and the taste is lifeless. If you spot these signs, don’t hesitate to return the bottle.


Does your wine taste stewed, flat, or bitter, like an over-brewed cup of tea? It might be “cooked.” This flaw happens when wine is exposed to high temperatures, which strip it of its character and leave it dull and unbalanced.

Cooked wine is common, especially during transport or poor storage. Corks can expand and push out slightly due to heat, and you might notice dried wine streaks on the bottle. If your wine smells raisiny or stewed, it’s likely cooked. Send it back and get a fresh bottle.

Corked wine remains one of the most well-known flaws, though it’s less common in the UK thanks to the rise of screw caps. Corked wine occurs when a natural cork is infected with a fungus that produces TCA (2,4,6-trichloroanisole).

The result? A damp, musty smell reminiscent of wet newspapers or a mouldy basement. Corked wine tastes muted and flat, with none of the vibrancy you’d expect. Estimates suggest up to 5% of cork-sealed bottles are affected. If you detect that unmistakable aroma, there’s no saving it—request a replacement.

Reduction is the opposite of oxidation—it happens when wine doesn’t get enough oxygen during production or ageing. Reduced wines often have a sulphur-like aroma, reminiscent of rotten eggs or burnt rubber.

The good news? Reduction can sometimes be fixed. Decant the wine and let it breathe for an hour, or try dropping a clean copper coin into the glass. The copper neutralises the sulphur compounds, improving the wine’s aroma. If the flaw persists, return the bottle.

Brett is a type of yeast that can affect wine, bringing out earthy or funky aromas. In small amounts, Brett can add complexity—think forest floor or leather. Some winemakers even embrace it.

But when Brett takes over, the wine becomes unpleasant. Imagine wet dog, sweaty socks, or barnyard odours. If you encounter these overpowering smells, it’s best to set the bottle aside and ask for another.

If your wine shows signs of any of these flaws, don’t hesitate to speak up. These issues are common and part of the natural unpredictability of winemaking. A good wine shop or restaurant should understand and happily provide a replacement. And if they don’t? There’s always another bottle—and another shop — waiting for you.

Talking of fine tuning your olfactory function, we wrote 

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