Wine waiters, often called sommeliers in posher restaurants, sometimes go through an elaborate performance before pouring you and your fellow diners a glass of wine. I know some people find it intimidating, but done well it can be great to watch. The waiter should first show you the label so that you can check that it is the wine and vintage you ordered. Some will offer to decant the wine.

Then they will open the bottle. Some will sniff the cork before pouring you a small sample of wine to try. Both of these are done to check if the wine is faulty. The most common fault is that the wine is “corked”. This is caused by TCA (trichloroanisole) a chemical compound found in natural corks and very occasionally in wood. I have never found sniffing the cork to be of any use, but others swear by it.

In the past corked wines were quite common, 2-10 per cent of wines depending on who you talk to. Some people can detect TCA in tiny quantities, others are far less susceptible. Very corked wines smell (and taste) mouldy, or of wet cardboard or dirty dish cloths. Others just smell of very little. Neither are pleasant.

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These days the manufacturing process is much better and faulty corks are rare to come across. Wines bottled with screw caps or plastic corks cannot be corked, yet the practice of offering a sample persists. If the wine is corked, the waiter should replace it with another bottle of the same wine. However, if you really don’t like the smell or taste of the sample you have been served, you could try politely sending it back. It might just be a horrible wine. Most good restaurants will replace it with something else, and return the bottle to the distributor.