There are a lot of wines out there that suck; tasteless, insipid, and not meant for human consumption. But what about a wine that should be good, yet turns out awful? Often times it's not that it's a lesser wine, but it has simply gone bad. Here's a brief rundown for what to look for when your wine isn't quite right.
What's challenging is that you won't know if the wine has gone bad until you pop the cork and have that first pour. And when you do, here are the things to look out for (use your senses!)
Take a look. Trust your eyes when the wine is in the glass. Look at the color; if it's a young white wine it should be a vibrant and very light lemony color. If it's a deep amber or gold and is only a year or two old, take notice. Oxygen may have taken hold and oxidized the wine to undrinkability. If it's a young red wine, look for tinges of brown. This could also foretell oxidization. Older wines should have a more aged, brownish tint to them, but wines that are a couple of years old should not.
Take a whiff. After that longing glance, give the wine a smell test. The 'nose' of the wine should be pleasant with notes of fruit or other elements that are indicative of the varietal. There should be nothing off about the smell. Terms like 'wet dog', 'wet cardboard', and 'vinegar' are often used. These are undesirables. Sometimes wine geeks can say a wine is 'corked', which basically means that the wine had a bad cork allowing something known as 'cork taint' into the bottle and makes the wine stinky and not good. The nose knows!
Take a swig. After seeing and smelling have passed the test, tasting is on deck. The wine should taste like it should. Hopefully there are no 'off' flavors. But there could be touches of oxidation which means it's past its prime and declining. If it has tinges of vinegar, pour it out.
When restaurants open a bottle and provide that initial taste, it's to give the diner a chance to test the wine. If it's off, bring it up to the server or sommelier for their opinion. According to Lettie Teague of the Wall Street Journal, not enough people send wine back if it's bad. If you want to try out a bad wine to know the taste, ask while at a wine bar, wine shop, or a restaurant if there are any corked or bad wines to experience. This can be a fun experiment, and luckily these places usually have a spit bucket nearby.