Wine faults: recognising them in the exam glass
Faults are examined twice over: as theory, where you are asked what causes them and how they are prevented, and in the tasting paper, where you may have to recognise one under time pressure and decide what to do about it. The harder skill is the second one, because the line between a fault and a deliberate style is thinner than most candidates expect. This guide covers the faults on the syllabus, how each presents, and the exam mechanics.
The faults you are expected to recognise
Cork taint is caused chiefly by TCA, a compound that can form in cork and in winery materials. It smells of damp cardboard, wet newspaper, or a musty cellar. Its most testable feature is what it does rather than what it adds: at low levels it may not smell of anything obvious, it simply mutes the fruit and leaves the wine hollow and short. It is harmless to drink.
Oxidation comes from excessive exposure to oxygen. Whites turn deeper gold or brown, reds turn brick or brown at the rim, fresh fruit disappears and is replaced by bruised apple, walnut, caramel and a sherry-like character. Poor closures, careless handling and old age all contribute.
Volatile acidity is largely acetic acid and ethyl acetate. At low levels it can lift a wine and add complexity, which is why many fine wines carry a trace of it. At fault level it reads as vinegar, or as nail varnish remover and pear drops for the ethyl acetate component.
Reduction is the opposite problem, a shortage of oxygen during winemaking or ageing, producing sulfur compounds. It presents as struck match, flint, rubber, boiled cabbage, or at worse levels rotten eggs. Its defining behaviour is that mild reduction frequently blows off with air, so a wine that smells reductive on pouring may be clean twenty minutes later.
Brettanomyces is a spoilage yeast giving farmyard, horse, sticking plaster, smoke and clove characters. It is the most divisive item on the list, since a small amount is tolerated or even prized by some drinkers in certain regions, while the trade broadly treats it as a fault.
Three further faults come up less often but are worth holding. Refermentation in bottle leaves an unintended prickle and haze in a still wine. Heat damage from poor storage or transport gives stewed, cooked fruit and may push the cork proud. Excessive sulfur dioxide catches in the throat and smells of a just-struck match, though it often dissipates with swirling.
The distinction that actually earns marks
The hardest judgement is not identifying a smell. It is deciding whether the smell is a fault at all.
Several classic wines are made deliberately oxidative. Oloroso Sherry, Tawny Port and the wines of the Jura are not faulty, they are the intended outcome of a chosen process, and describing one as oxidised in an exam answer is a real error. The same applies to a traditionally made Rioja, whose long ageing in older American oak produces an oxidative note that belongs to the style. You can read the wider context in fortified wine production.
Reduction sits in similar territory. A struck-match character in a fine white made under reductive conditions is often a stylistic signature rather than a defect, particularly where the winemaker has chosen it. The examinable distinction is between a note that integrates or blows off and one that dominates and does not.
The safest formulation in a written answer is to name the character, name the likely cause, and then say whether it is at a level consistent with style or with fault. That structure earns the mark either way.
What to do with a faulty sample in the tasting exam
If a wine in front of you seems faulty, do not write a tasting note on it and hope. The established practice is to raise your hand and tell the invigilator, who can supply a replacement sample. Examiners expect this, and candidates lose marks by silently describing a corked wine as a short, hollow, fruitless example of its style.
Two practical points follow. First, taste and check early rather than at the end, so there is time to swap the glass. Second, distinguish a faulty sample from a wine you simply find difficult, because asking for a replacement for a wine that is merely austere costs you time. Procedures and invigilation rules can be revised, so confirm the current wording in your candidate handbook before exam day.
How faults show up in the theory paper
Theory questions tend to run in the other direction, from cause to consequence: what causes TCA, how a winery limits oxidation, what role sulfur dioxide plays, why some producers accept a degree of Brettanomyces. Answers should name the mechanism rather than the smell, and connect it to a winemaking or storage decision.
Prevention is the recurring theme. Sound cellar hygiene, temperature control, careful use of sulfur dioxide, well-maintained closures, protection from oxygen during transfer, and cool stable storage all appear as answers to more than one question.
Where to go from here
Faults sit directly on top of the tasting grid, so work through them alongside the WSET SAT explained and common WSET tasting mistakes, which covers the related habit of over-calling a fault. If you are preparing the Level 3 tasting paper specifically, the tasting paper walkthrough shows where fault assessment fits in the sequence.
FAQ: wine fault questions
What does a corked wine smell like? Damp cardboard, wet newspaper or musty cellar. At low levels it may add no smell at all and simply strip the fruit, leaving the wine hollow.
Is volatile acidity always a fault? No. Low levels are common in fine wine and can add lift and complexity. It becomes a fault when vinegar or nail varnish characters dominate.
How do you tell reduction from a permanent fault? Mild reduction usually blows off with air or vigorous swirling. If the character persists and dominates after aeration, treat it as a fault.
Is an oxidative style the same as an oxidised wine? No. Oloroso Sherry, Tawny Port and Jura wines are deliberately oxidative and are not faulty. Oxidation is a fault only where it was not intended.
What should you do if an exam sample is faulty? Raise your hand and ask the invigilator for a replacement rather than writing a note on the faulty glass. Check the current procedure in your candidate handbook.