REFERENCE
That smell in the glass — is the bottle faulty, or is it meant to be like that? Here's what each common wine fault smells like, whether it's just your bottle or the whole case, and the crystals and sediment that only look wrong.
Know what to open tonight — and never miss a wine at its peak.
Log the bottles in your rack and Saignée tells you which are hitting their peak, so a corked bottle is a rare bit of bad luck, not a forgotten wine slipping past its best. Try Saignée free →
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7
Common wine faults
25
Tell-tale smells
6
Harmless look-alikes
First, the good news: a faulty wine is unpleasant, not dangerous. Every fault below makes a wine taste or smell wrong, but none will make you ill — so you can taste, judge, and pour it out with a clear conscience.
Bad luck
Bad luck rather than a bad wine — a single cork or a single bottle's rough journey. If you bought it somewhere reputable, it's fair to ask for another; the next bottle is very often fine.
The classic “corked” wine — nothing to do with bits of cork floating in your glass.
Smells & tastes like
What causes it: A compound called TCA (2,4,6-trichloroanisole), usually from a tainted cork, that mutes the fruit and adds a musty smell.
The wine has “gone flat” from air, the way a cut apple browns.
Smells & tastes like
What causes it: Too much air — a failing cork, a bottle left open too long, or age simply catching up with it.
Cooked wine tastes dull and stewed, with the life boiled out of it.
Smells & tastes like
What causes it: The bottle got too hot in transit or storage — a hot car, a sunny shop shelf, an un-air-conditioned warehouse.
Rarely talked about, but the reason dark bottles exist.
Smells & tastes like
What causes it: Too much light — sunlight or shop fluorescents hitting a wine bottled in clear or pale glass. It’s why so many wines come in dark green bottles.
From the winemaking
These come from the winemaking, so another bottle of the same wine may show the same thing. Whether it counts as a fault can also be a matter of degree and taste.
The one fault you can often fix yourself — see below.
Smells & tastes like
What causes it: The opposite of oxidation — too little oxygen during winemaking leaves behind smelly sulfur compounds.
A pinch can be part of a wine’s character; a lot is a fault.
Smells & tastes like
What causes it: Acetic-acid bacteria nudging the wine toward vinegar; a trace adds lift, but a noseful is a flaw.
Fault or feature depends on how much there is and who’s drinking.
Smells & tastes like
What causes it: A rogue yeast (Brettanomyces) making funky, animal aromas — divisive, and even prized in small doses in some reds.
These are the widely-taught wine faults and their classic give-away aromas (the fault vocabulary used in WSET-style tasting). Treat them as a guide, not a lab test: perception is personal, and a trace of some faults — a little Brett or volatile acidity — is part of the character of certain wines rather than a flaw. When in doubt, a wine you simply don't enjoy isn't necessarily faulty. Last reviewed 2026-09-09.
Can you save a bad bottle?
Usually not — cork taint, oxidation, heat damage, and light strike are terminal. The one exception is reduction (rotten egg, struck match): give the wine plenty of air in a decanter, or try the old trick of a clean copper coin, and a mild case can blow off. And before you give up on a quiet young wine, ask whether it's faulty or just closed — an hour of air often answers it.
The tell-tale aromas, A to Z — with the fault each one points to and whether it's likely just your bottle or the whole case.
Don't panic
Some of the things that alarm beginners the most are completely harmless. Here's what not to worry about.
What worries people: Tiny clear or reddish crystals on the cork or at the bottom of the glass.
Harmless tartaric-acid crystals — a sign the wine wasn’t over-processed, not ground glass. Decant off them if you like; they’re tasteless.
What worries people: A dark, gritty deposit in the bottom of an aged bottle.
Completely normal in older wine. Stand the bottle upright for a day, then decant the clear wine off the sludge.
What worries people: “Contains sulfites” on the label, often blamed for headaches.
Nearly all wine contains them as a standard preservative, and for most people they don’t cause the classic red-wine headache. A true sulfite sensitivity is uncommon.
What worries people: Flakes of cork floating after you pull a dry or crumbly cork.
Not the same as a “corked” wine — that’s a smell, not floating debris. Fish the bits out; the wine itself is fine.
What worries people: A good bottle that smells muted and gives very little at first.
Often just young and shut down rather than faulty. Give it air in a decanter — or more time in the cellar — and it usually opens up.
What worries people: A whiff of kerosene or petrol in a mature Riesling.
A prized hallmark of age in Riesling, not a fault — the same tertiary, age-driven note the flavor wheel describes.
Not faulty, just past it?
A wine can be sound but simply tired. See how long an opened bottle really lasts, or brush up on the aromas of a healthy wine so you can tell “aged” from “off.”
Trust your nose first. A sound wine smells clean, even if it isn’t to your taste; a faulty one usually announces itself. The give-aways are musty wet cardboard (cork taint), bruised apple or a flat, sherry-like note (oxidation), rotten egg or struck match (reduction), stewed or port-like fruit (heat damage), and vinegar or nail-polish (volatile acidity). If the fruit smells muted, cooked, or genuinely off — not just closed — the bottle is probably faulty.
No — and this trips up almost everyone. “Corked” means cork taint: a compound called TCA, usually from a tainted cork, that makes the wine smell of wet cardboard, damp basement, or moldy newspaper and strips out the fruit. It’s a smell, not floating debris. Actual flakes of cork from a dry or crumbly cork are harmless — just fish them out and drink the wine.
Vinegar and a sharp nail-polish (acetone) lift are volatile acidity — the wine edging toward vinegar. Rotten egg, struck match, or burnt rubber is reduction, from a lack of oxygen during winemaking. The good news: reduction is the one fault you can often fix. Give the wine plenty of air in a glass or decanter — some people even drop a clean copper coin in for a moment — and mild reduction can blow off. Volatile acidity, once it’s obvious, does not.
A faulty wine is unpleasant, not dangerous. Cork taint, oxidation, reduction, heat damage, volatile acidity, and Brett all make a wine taste or smell wrong, but none of them will make you ill — the alcohol and acidity keep wine from harbouring the bugs that spoil food. The worst a corked or cooked bottle does is waste the wine. Pour it out because it tastes bad, not because it’s a health risk.
Neither is a fault. The little clear or reddish crystals (“wine diamonds”) are harmless tartrates — a sign the wine wasn’t heavily processed, not ground glass. Sediment in an older red is just the wine throwing a deposit with age: stand the bottle upright for a day, then decant the clear wine off the bottom. Both are cosmetic.
Usually not. Cork taint, oxidation, heat damage, and light strike are terminal — nothing at the table brings the wine back. Reduction is the exception: air, a decant, or the copper trick can clear mild cases. And remember the false alarms — a young wine that smells muted may just be “closed,” and open up beautifully after an hour in a decanter or a few more years in the cellar.
Know what to open tonight — and never miss a wine at its peak.
Log the bottles in your rack and Saignée tells you which are hitting their peak, so a corked bottle is a rare bit of bad luck, not a forgotten wine slipping past its best.
Free Taster: up to 100 bottles · 20 AI scans · 10 pairings / month
Free forever · No credit card