If you’ve ever smelled a musty wine or discovered your white to be tinged with brown, you may have a faulty bottle. A little experience will help you determine the cause – and what to do about it.

Here are five common problems and where they fall on the spectrum of concern.  

1. Corked Wine 

Pop the cork, pour the wine and, hmm. What’s that smell?  A vision of your grandparents’ basement pops to mind. The culprit is most likely “TCA,” the acronym for 2,4,6-trichloroanisole. TCA usually, but not always, arises from the contact between a natural cork closure and wine. When levels are detectable, the natural chemical compound first attacks your sense of smell. “Wet basement or newspaper,” “musty,” and “moldy newspaper” are typical descriptors. On the palate, TCA masks fruit and dulls vibrancy. While it won’t hurt you, too much ruins the pleasure of the wine.  

TCA on the spectrum: People have different levels of sensitivity to TCA. Down the sink to one, may be down the gullet to another. 

2. Maderized or Cooked Wine

Maderized or cooked wine results from heat exposure. Too much will literally “cook” the juice, leaving reds tasting roasted, stewed, jammy, or evocative of prunes and raisins. Whites turn dull, nutty, and brown. Another clue: a partially dislodged cork. It indicates hot air expanded inside the bottle. Unfortunately, this can happen anywhere, from the shipping company to the end user: a delivery truck leaves wine in the hot Texan sun; a retail stockist stores bottles in a sun-filled window; an Italian restaurant keeps Sangiovese in the kitchen (yes, this is a real and common thing); the consumer bought a case of wine at a winery and forgot about it in the trunk of her car.

Cooked wine on the spectrum: If a wine has been maderized enough to notice it, toss it. 

3. Oxidation

Ever pour a young white wine, expecting a sparkling lemon hue, only to find it brown and ruddy? This visual clue indicates possible oxidation, or excessive oxygen exposure. Oxidation can start as far back as the winemaking process or within hours of uncorking the bottle. Restaurants with extensive by-the-glass programs often serve oxidized wine to customers who don’t know any better. (If your wine doesn’t taste right, always check how long the bottle has been open.) If the problem came from the producer, you’ll know when you it as soon as you open it. Like whites, reds lose their luster turning brick-orange, while tasting dull and flat. White aromas suggest cider or sherry. 

Oxidation on the spectrum: Oxidation comes in degrees of intensity, such that a touch of it may be misinterpreted as a jammy wine from a hot vintage. But if color, aroma and flavor have noticeably diminished – and it just doesn’t taste good – dump it. Or else make wine vinegar. 

4. Old versus Mature 

We’ve all tucked away a special bottle for a future celebration – and either forgotten about it or never felt any moment to be deserving of opening it – only to discover it faded long past its prime. Given the majority of consumers drink wine the day they buy it, most bottles nowadays aren’t meant to age.  If you’ve had the bottle awhile, and there’s a discernable loss of character and freshness, it’s likely the wine has passed on to a higher realm. Especially with easy-drinking whites. 

Age on the spectrum: Be careful when gauging if a wine is older or just old. It takes experience, not to mention, appreciation for mature wine is a subjective art. Some consumers prefer drinking young, fruity, tannic wines, while others enjoy the savory, mellow character of older Bordeaux. But if the wine is charmless and flat, your taste buds will tell you. 

5. Brettanomyces or “Brett”

Before anyone knew a strain of spoilage yeast caused aromas of “band-aid,” “horse blanket,” and “barnyard,” famous producers infected with it, from Bordeaux to Barolo, were earning high scores from wine critics. Château de Beaucastel from Châteauneuf du Pape is commonly cited as an example. Nowadays, most modern winemakers try to avoid Brettanomyces yeast in their wines, in part, because it’s hard to control in a wine and can take over a winery. And once it spreads around a winery, it’s hard to eradicate. However, new technologies – wine additions – are helping winemakers remove or reduce Brett when first detected. It will be unlikely to encounter wines with it in the future.

Brett on the spectrum: Many wine lovers enjoy “barnyard” in small doses, while a hint of it turns others off entirely. While it’s a matter of taste, too much Brett masks a wine’s fresh flavors.