Common wine faults: how to spot them and respond in service

A wine fault is not solved by showing how much the team knows. It is solved by protecting the guest experience, checking the problem calmly and making a quick decision. On the floor, the goal is not a laboratory diagnosis. It is to recognise reliable signs, rule out service errors and replace the bottle when appropriate.

Fault, development or preference

A wine may be intense, mature, briefly reductive after opening or simply not to the guest's taste without being faulty. Before removing it, check temperature, glassware, time open and a second sample. Never argue with a perception: thank the guest and verify it.

Cork taint and musty aromas

TCA commonly suppresses fruit and recalls damp cardboard, a cellar or mould. It can be subtle. If fruit seems strangely absent and that damp character appears, open another bottle. Air or a clean glass will not fix it. The [Australian Wine Research Institute](https://www.awri.com.au/industrysupport/winemakingresources/sensoryassessment/recognition-of-wine-faults-and-taints/winefaults/) identifies TCA as the principal compound behind cork taint.

Oxidation and reduction

Unwanted oxidation may show muted fruit, bruised apple, nutty notes and darker colour. In some fortified or deliberately oxidative styles, these characters are expected. Reduction may smell of egg, rubber or struck match. It can improve with air, but a dominant character that persists should not reach the table.

Volatile acidity and Brettanomyces

A clear vinegar or solvent note may indicate high volatile acidity. Brettanomyces can produce medicinal, animal or leathery characters, but not every rustic aroma is Brett. Staff do not need to name the compound; they need to notice when it overwhelms fruit and damages the experience.

A five-step service protocol

1. Listen and remove the glass without debate. 2. Check glassware, temperature and bottle. 3. Taste a small sample with another responsible team member. 4. Open a second bottle or offer an equivalent alternative. 5. Record the wine, lot, supplier and decision to identify repeat cases.

What to say to the guest

One sentence is enough: “Thank you for telling us. I will check the bottle and replace it straight away.” Do not turn the table into a technical tasting. If there is no fault but the wine is not a fit, offer an alternative and keep quality incidents separate from personal preference.

Turn incidents into learning

Track how many bottles are removed, why, and whether the issue repeats by wine or lot. Winerim can connect the incident with the wine record, stock, supplier and available substitute. The [service guide](/en/wine-library/service-guide) and [recommendation scripts](/en/article/wine-recommendation-scripts-restaurant-floor) help every shift respond consistently.

Frequently asked questions

Should every rejected bottle be replaced? If there is a reasonable sign of a fault, yes. If it is preference, follow the restaurant's hospitality policy without labelling the wine faulty. Can decanting remove a fault? It cannot remove TCA, oxidation or volatile acidity. Brief aeration can soften some reductive aromas, but it should not hide a persistent problem. Continue with [Learn wine](/en/learn-wine), the [Glossary](/en/wine-library/glossary), [Service guide](/en/wine-library/service-guide), [Wine Library](/en/wine-library) and [demo](/en/demo).