Is My Wine Bad?

Learn a bit more about detecting wine faults. When should you return your wine at a restaurant?

6 Common Wine Faults You Can Detect:

Is your wine bad? Well, it’s a complex question to answer. Most wine is not faulted, but if you are drinking one that is, it’s important to know. Especially as in most cases you can just return it and get a new bottle or glass (just like returning a damaged product to Amazon or the store).

There are a few common wine faults that you can detect. If you do, it’s not that the wine is bad because it was made poorly (that’s another story), it’s that something has happened to the wine either during fermentation or afterwards to the bottle. Here are a few to look out for:


Cork Taint:

Cork taint results from the intrusion of the bacteria creating a musty smelling compound called 2,4,6-Trichloroanisole. The name comes from the fact that this bacteria often lurks in corks and thus gets into the wine after it’s finished and bottled. It can also just reside in the winery or other places and get into the wine. The result is that aroma and flavours are muted and mostly, you’ll get a whiff of moldy basement or musty socks. Typically, you can return the wine to the store or send back the bottle at a restaurant for a new one.

1 in 12 bottles in the past have been imagined to carry cork taint, but there are advances in cork technology that are helping here. Stelvin closures (screw cap) and DIAM corks are helping make sure less wine is “corked”


Brettanomyces (or Brett for short) is a bacteria that can get into the winemaking process delivering aromas of “mouse, horse blanket, barnyard or sweaty bandaid.” In small concentrations, it can actually add complexity to the wine and many brewers and beer connoisseurs love a bit of brett. If you are sensitive to brett or if there is way too much in the wine, it becomes a fault. The Pinot Noirs of Burgundy and many wines from the South of France are notorious for being a bit “bretty”

Smoke Taint:

Did you know approximately 20% of ppl can’t detect smoke taint in wine? That’s wild, but good for them. They can enjoy so much more wine than everyone else! Smoke taint is a bit different than enjoying a wine that shows a “smokey” component in its aromatic profile. Smoke taint can come off as bitter and taste/smell like a wet ashtray. Again, most aroma and flavour components are hidden and overtaken by smoke. This is becoming more common in regions like California and the Okanagan due to climate change.

Isovaleric Acid:

Brettanomyces can create isovaleric acid. It’s known also to be a product of the fermentation of amino acids producing a sweaty or cheese note. Here also in small quantities, this can add complexity to wine character, but can become overwhelming and pungent.


Winemakers control their wine’s exposure to oxygen thoughtfully and carefully. Wines need a small amount of oxygen to add texture and certain aromatics. This often comes from fermenting a wine in concrete or neutral oak barrels that allow a small amount of O2 to access the juice through the porous vessel. Too much exposure to oxygen can lead the wine to giving off a bruised apple aroma which is quite unpleasant. This can also happen from a faulty closure and wine being exposed to the air as it ages.

Volatile Acidity:

Like nail polish remover. Bacterial spoilage in wine can lead to large amounts of acetic acid being produced. This is the smell of vinegar. Production of ethyl acetate via the same route delivers the smell of nail polish remover. Like many others, in small quantities, VA can help “lift” the aromatics of your wine and enhance the experience, but it can very soon become overwhelming. Some people are more sensitive to VA than others.

LEARN MORE about wine faults and sensory evaluation with a Master Of Wine. CLICK HERE to take the class:

Meet Rhys Pender MW in the video below and learn more about the class.