Wine professionals acknowledge that at least 1 out of 20 bottles of wine—perhaps more like 1 out of every 10—is corked. That means flawed. Gone bad. Worthy of a refund.
Have you opened 10 bottles of wine in the last year? How many have you sent back? Or, better put, how many have you not sent back because you had no idea... or because you didn't want to be awkward, because you didn't want to look dumb.
Cork taint is just one wine flaw you can learn to identify; below we list seven of the most common. Knowing what to look out for and how to ask for an alternative bottle will help you drink much better.
Don't look at the cork; don't smell the cork; don't look for bits of cork in your glass—none of these will tell you if a wine is corked. The only way to identify cork taint is to smell and taste your wine. TCA—that's 2, 4, 6-trichloranisole for all you chem-nerds—is a compound that gets into cork and imparts a musty odor in the wine. Stick your nose in your glass and sniff around for notes of moldy cardboard, musty basement, or mangy sponge, all common indicators of TCA. Low levels of TCA can also "mute" a wine's other delicious aromas, so if your wine seems particularly DOA, ask for a second opinion or another bottle to compare.
"Cooked" means that the wine has been overheated for a significant period of time. Warm temperatures (even those just over 75 degrees) dull or flatten a wine's flavor; in extreme situations the wine becomes stewed, prune-like or raisin-y in flavor. This is when it pays to know where your wine is coming from. Wine storage is super-important and all too often overlooked. A shelf in the window of a shop with the sun beating down on it? That wine, sadly, is screwed. A rack right next to the kitchen stove? Ditto.
Warning signs of cooked wine include a cork protruding from the top lip of the bottle or wine seepage around the cork, which indicates that the wine was heated and expanded, pushing the cork or wine out of the bottle.
Think of a crisp, green, Granny Smith apple. Now leave it cut up and lying out on the counter for a day. It turns brown and the flavors taste, well, brown, too: dried up, worn-out and cider-like. Oxidized wines are the same way, and they often have a nutty flavor. Older wines bottled with cork closures will naturally have some pleasant, subtle oxidative flavors as the cork has let in a tiny bit of oxygen over the years. However, young wines should be fresh and crisp.
Sniff for Band-Aids and barnyards. If a wine smells like either of these, it's affected with a yeast called brettanomyces (aka brett), which, like any yeast, can live all around us. In particular, brett likes hanging out in barrels in wineries, and once it's in your winery, it's notoriously difficult to evict. In fact, for this reason, some wines have become well-known for their distinctly bretty character. Some people (this author included) enjoy brett in small doses, as it can also convey meaty and spicy notes of bacon, leather or cloves. If, however, your wine smells like straight-up manure, feel free to request something different. Chances are good other bottles of the same wine will be likewise affected.
VA stands for Volatile Acidity; it is naturally present in all wines in small quantities and usually causes no problems. But sometimes, when bad bacteria like acetobacter (which turns wine to vinegar) are in the winery, a sort of wine infection occurs between the bacteria, alcohol, and oxygen. In these cases, VA goes off the deep end and the wine's fresh, fruity flavors are destroyed with a sour, vinegary character left in its place. VA can also smell like nail polish. That's not a good thing.
Sometimes, a wine literally starts fermenting again in the bottle, leaving the wine spritzy and off-flavored. This happens when there are yeast and sugar still in the bottle. The yeast get hungry! And they eat the sugar, just doing their job. But the byproducts of fermentation are alcohol and carbon dioxide, so your wine will be a tiny bit bubbly. Bacteria left in the wine can also happily eat away at other normal components of a wine and spit out carbon dioxide and other off-putting aromatics. This is why wineries must practice great sanitation and typically use a little bit of sulfur and/or filtration to curb the yucky bacteria.
An emphatic note: Sulfur is not inherently a flaw. Sulfur is not inherently bad! Reasonable doses of sulfur in the winemaking process are important: sulfur helps prevent other flaws (see above) because it acts as a natural preservative and keeps bacteria at bay. Asking for a wine to be made without sulfur is a little like asking for your dinner to be made without the cook washing her hands. Risky.
However, like all things, too much of a good thing can turn bad. Excessive sulfur use will give wine nasty aromas of burnt matches or rubber. Two other sulfur-related flaws have to do with tricky chemical reactions that'll result in a wine that smells like rotten eggs or garlic and onions. Woof.
So you think you've spotted a flaw. Now what?
Any of the above warrants asking for a new bottle. Note: It's always polite to do so before you've polished off most of it!
In all cases, start your conversation at the time of purchase with a clear, open statement about your tastes and preferences. Don't be afraid to ask questions or seek advice. This original dialogue with the salesperson, server or sommelier will help ensure you head down the right path in the first place. When you first taste the wine (whether at home or in a restaurant), take your time. Don't be afraid to sniff, swirl, and swish the wine around in your mouth—a lot! If you're at all unsure about what you're smelling or tasting, mention your concerns right away and ask for the professional's opinion. A cool, vague, casual approach works best: "Hmm. I'm not sure about this wine. Would you mind tasting it and letting me know what you think?"
A good salesperson will know the character of the bottle well enough to ascertain whether the wine is showing "correctly" or is flawed. A flawed bottle will receive a swift replacement. Don't feel bad about this—the restaurant or shop can usually return flawed bottles to the distributor.
If the wine is sound, but just not to your personal taste, that can present a trickier situation. In many cases, the sommelier or salesperson will happily suggest something new and take the original bottle back. However, if the wine is particularly expensive, this may be harder for her to justify. In some states, returning alcohol to a retail shop is prohibited, so only exchanges for flawed bottles may be possible.
The bottom line is that there's no harm asking. Even if you're wrong, and the wine is perfectly good, who cares?! You'll likely learn a little about why the wine is tasting or smelling the way it is, and you'll be better able to enjoy it for what it is. And hey, in roughly 1 out of 20 cases you'll be right! The new bottle—and your subsequently better night—will make any anxiety in asking absolutely worth it.