You don’t have to be connoisseur to see if a wine is one you will like. Actually, your role on first tasting a wine that the wait staff pours, is to determine if the wine is spoiled or not — it should not smell or taste unclean. If the wine is “unclean” then it exhibits a fault such as being oxidized (sherry-like), sharp and vinegary, very flat (no fruit aromas), exhibiting cork taint (wet cardboard or dirty socks) or having Brettanomyces odors (wet dog, horse stable, rotting vegetation). If you don’t judge it by smell as having any of the above off odors, then the next step is to determine if the wine is relatively in balance for its type.
It is reasonable to assume any wine a restaurant is trying to sell is not too unbalanced with respect to acidity, tannins, sweetness, or bitterness. Taste is a combination of what the tongue senses and what aromas rise up from the back of the mouth and throat to the odor detection centers of the brain. The tongue senses more than the 4 things you commonly think of as tastes: sweet, salt, acid (sour) and bitter. There are also taste receptors for fat, capsaicin (spicy heat from peppers) and savory or umami (pronounced oo-MA-mee) tastes. Wine rarely has tastes of salt, capsacin, or fat so these terms do not appear on tasting sheets except perhaps as peppery on the palate. Tannins give more of a “mouth feel” (astringency and dryness) rather than a taste, although sometimes “green, unripe” tannins from cool weather grown or unripe grapes can be perceived as bitter.
When first tasting a wine, swirl some of it around in your mouth like a mouthwash. Try not to judge the wine from that first swish. Professional wine tasters actually spit that first wine out. It clears the palate from a previous wine. You can be polite and swallow that first swish. The purpose of this “swish” is to cleanse the mouth’s taste receptors of whatever was last on them, acid, sweet, tannin, toothpaste, mouthwash, coffee, tobacco etc. Then take a second drink and try to describe to yourself the basic tastes and flavors of the wine. Have you ever had the experience that the first taste of a wine seems bad, but subsequent tastes are much better. When this happens you have probably just brushed your teeth, used a mouthwash or have just eaten something spicy, sour or sweet.
It can be difficult for less experienced wine drinkers to describe taste faults in an unclean wine. Wine should not have any offensive smells. You should at least be familiar with oxidized wine in which the color rim is brownish and it smells burnt and nutty. While some fortified wines like Sherry, Port, Marsala, and Madeira for instance are intentionally oxidized yielding a bruised apple or nutty smell. This aroma and taste is generally considered a fault in a wine and a reason to return it for another bottle. Try to be familiar with the taste of Sherry.
Sometimes you may taste a wine and while you cannot put your finger on it, it just does not taste right. If you are an experienced wine drinker you may be able to differentiate whether it is a wine fault or it tastes “off” just because of recent taste bud stimulation by something that clashes with wine. In the latter case do not return the wine because it is faulty but rather try to swish the wine and repeat the taste.
When should you send the bottle back in a restaurant and ask them to replace the bottle?
Fortunately, “bad wine” (as opposed to wine that is not very good) does not happen frequently with today’s modern wine technology. However it still occurs and you will taste it on occasion. There is a difference between just not liking a particular wine and getting one that is “spoiled“; you should know the difference. Any purchased wine may have more tannins than you like or be more acidic (sour) than you prefer. It could be less sweet or fruity than you are used to, or too sweet for your tastes, but these are not reasons to send the wine back. Wine that is unbalanced to your taste in tannins, acid or sugar will not have off-smells; you will just notice a taste you do not care for. To send the wine back or even to ask the wine server to check the wine by smell and taste, you want to have some idea of what the most common “off tastes” in spoiled wine are. Almost always these can be detected by aroma and then confirmed by taste.
If you really cannot tell if a wine is bad but you really don’t want to drink it, ask the wait staff to give it to someone on the staff such as the manager, the bar tender, or a sommlier that can judge whether the wine is spoiled or not. If they say it is ok, go ahead and accept it and vow to learn more by tasting, tasting ,tasting!