how to sniff out wine faults
September 17, 2021

6 Common Wine Faults and How to Sniff Them Out

For many of us, finding a fault in wine is as simple as whether or not we like it. While the perception of a wine’s quality is subjective — what some consider a flaw, others consider a virtue — there are some telltale signs that a wine has passed its prime. So how do you know if a wine has a fault and it isn’t something intentional? This sometimes makes it hard to conclusively state “this wine is bad”. Nevertheless, here are 6 common wine faults and how to sniff them out. Plus, some other faults that aren’t really faults. 

Wine Flaw vs Wine Fault

To start, let’s define the difference between a wine flaw and a wine fault. If you’re drinking a wine and notice something that isn’t normal for that variety or that region, it can be considered a wine fault. This can be a slight imbalance in acidity or sweetness or a color that is slightly off. Nevertheless, the wine is still drinkable.

When there is too much of a flaw and it covers up all other flavor characteristics of a wine, this is now considered a wine fault. It’s important to note however that wine faults aren’t bad for us. However, they do taste bad. So how does this happen? It’s usually linked to interior chemical conversions that are sped by too much oxygen or fluctuations in temperature. 

6 Common Wine Faults

We’ve defined the difference between a flaw and a fault and how the latter happens. Now it’s time to go into the common wine faults you may come across during your wine journey. Luckily, you don’t always have to taste the wine (of course this will prove any suspicions) to know there’s a fault as most can be detected by smell. 


The most common fault is oxidation. If you’ve ever come across a bottle of wine that smells like vinegar or nail polish remover, your wine has likely oxidized. Another sign is the color of the wine: white wines will have a brownish color whilst reds will be brick-orange. As the name suggests, oxidation — also known as volatile acidity — is caused when wine is exposed to too much oxygen converting sugar and alcohol into acetic acid. There are of course degrees of oxidation: exposing wine to oxygen, such as when swirling or decanting, helps open up the wine. However, just like when you slice open an apple and it starts to turn brown, when you leave wine out for too long it starts to go bad. 

So how do you prevent oxidation? The short answer is proper storage. This means storing unopened bottles in the right conditions and resealing opened bottles as soon as you can. If you have unopened bottles with cork closures, store them on their side to avoid drying out the cork. 

infographic showing fresh red wine and oxidized red wine

But if you’ve opened a brand new bottle and it’s oxidized, it likely occurred during the winemaking process or during transit. If this is the case, you can either return the bottle if you’re at a restaurant or get in touch with the store you bought it from to request a replacement or a refund

Interestingly, white wines are more susceptible to oxidation because the higher tannin levels of red wines act as a buffer. It’s also worth noting that some volatile acidity is intentional. If you’re tasting balsamic vinaigrette in your red wine, this is a sign that the winemaker has used volatile acidity intentionally. While this taste isn’t for everything, it doesn’t automatically indicate a wine fault.


The next wine fault is the opposite of oxidation: reduction occurs when the wine hasn’t been exposed to enough oxygen. At lower levels you might smell notes of a struck match or smoky gunflint, but at higher levels it can smell like rotten eggs or dirty drains. This is often caused when winemakers add excessive amounts of SO2 to help preserve fresh fruit aromas and add complexity, however it also can act as an antioxidant. 

Luckily, these off aromas usually dissipate once you aerate the wine either by swirling it in your glass or decanting. But if even after an hour of decanting and the off aromas are still present, it’s best to get in touch with the store you bought the wine from. 


Also known as cork taint, corked wines are the second most common wine fault. The smell of wet newspaper, moldy cardboard, damp basement, or wet dog are all indicators of corked wine. This is caused by TCA (2,4,6-trichloroanisole), which develops when plant phenols from natural cork are exposed to chlorine, a common sterilizer in the wine industry. 

Whilst not physically harmful, cork taint renders a wine undrinkable. This is also why there has been a shift within the industry to Stelvin caps as it eliminates the risk of cork taint. If you ever come across a bottle you think is corked, rest assured knowing that it wasn’t caused by your handling. Get in touch with where you got your bottle of wine to notify them of the issue and request for a replacement. 


Maderized, or cooked, wine occurs due to too much exposure to heat or a series of temperature spikes. Before even opening the bottle you can see signs that the wine might be maderized. If you have a cork closure, the cork might be slightly sticking out from the bottle as heat pushes it up. Likewise, with Stelvin closures the cap can be popped up. These are also signs that the wine may also be oxidized as the seal is compromised. 

Once pouring a glass, notice if the wine smells jammy or as if it’s exclusively made with dried fruits. These are indicators that it’s cooked. To prevent this from happening remember to store your wines properly and keep them away from direct sunlight and appliances such as fridges and ovens. In short, the least amount of temperature fluctuations the better. 


Lightstrike, or UV damage, happens when wine has been exposed to too much light. This causes the wine to smell like a wet wool sweater and is a common fault in delicate wines like Champagne, Pinot Grigio, and Sauvignon Blanc. This is why many winemakers opt to use dark green bottles to help protect their wines. Nevertheless, it’s always best to store your wines in a dark place to avoid lightstrike. 

Microbial and Bacterial Taint

Microbes and bacteria are often used in winemaking to add more depth and flavors to wine. However, you can think of them like spices: they add an appealing complexity but too much becomes overwhelming. When these colonies become too aggressively present during the winemaking process, you start to get aromas that are mousy or reminiscent of hay bales. 

Faults That Aren’t Faults 

example of tartrate crystals and sediment in wine

We all know wine is a matter of preference. Some prefer red over white, some prefer bold fruity flavors while others prefer light and herbaceous notes. The same can be said for faults. While we outlined some undisputed wine faults above, there are some instances where what we think is a fault is simply a matter of preference. So here are some common instances where a wine fault isn’t in fact a wine fault. 

Tartrate Crystals

During the winemaking process, wine goes through a series of processes to help stabilize it for its intended shelf life. Despite this and possible temperature fluctuations, wine can form natural salts that precipitate or stay floating in the wine. These are completely harmless but do make the wine less pleasing to look out. If you really want to get rid of these crystals, you can pour your wine through a filter to catch these crystals. 


Brettanomyces, or brett for short, is a type of wild yeast that can be hard to control and eradicate from a vineyard once infected. It’s often used in winemaking because it adds a unique complexity to wine and has played a pivotal role in some of the world’s most prestigious appellations, most notably the Southern Rhone Valley. 

However, brett can cause aromas that smell like a farmyard or sweaty saddle and can have a metallic taste. It’s because of this that the use of brett polarizes the wine industry because what is a beautiful funky note to one is beastly to another. In other words, it’s a love or hate thing. 


If you’ve ever opened a bottle of red wine and notice dark, grainy material floating in the bottle or in your glass, these are sediments. They can be caused by either of 2 reasons. The first is that producers want to preserve flavors and textures so they don’t filter or fine their wines. The second is the result of aging when acid, tannin, and color compounds bond within the wine and fall out. These are perfectly safe to consume but if you want to filter them out, you can simply decant your bottle before serving. 

Watch our in-house wine experts talk about how to tell if your wine has gone bad in the video below:

Of course it’s never pleasant to open a bottle of wine and realize it’s not drinkable, but it’s important to remember that it’s a natural process. After all, wine is something that constantly evolves as it ages. While some wines can age for decades, most wines are designed to be enjoyed within a few years. 

Nevertheless, we believe you deserve a great wine, every-time. That’s why we have our Wine Quality Guarantee in place: if you are in any way not satisfied with the wine you’ve purchased from us, we will replace the item or refund your payment. Learn more about our Wine Quality Guarantee here

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