Not all wine is ideal for storing. If it's been in contact with air for too long or has a tainted cork, the liquid inside has turned and should not be consumed. Here are a handful of telltale signs that might indicate a good wine has gone bad.
- The smell is off. If a wine's aroma is moldy or resembles a musty basement, wet cardboard, or vinegar, it's turned. A heavy raisin smell is another bad signal.
- The red wine tastes sweet. If the bottle of red wine has the aroma of Port or tastes like dessert wine (even though it is neither of those two things), it has been overexposed to heat, and is therefore undrinkable.
- The cork is pushed out slightly from the bottle. That's a sign the wine has overheated and expanded within the bottle.
- The wine is a brownish color. A brown hue in red wine demonstrates that the liquid is past its prime. White wines that have darkened to a deep yellow or brownish straw color are usually oxidized.
- You detect astringent or chemically flavors. Wine that lacks fruit, is raspy, too astringent, or has a paint-thinner taste is usually bad.
- It tastes fizzy, but it's not a sparkling wine. A still wine that is fizzy or effervescent has undergone a second fermentation after the bottling and shouldn't be enjoyed.
One last word of advice: Always smell and examine the actual liquid. Although the term "corked"  commonly refers to tainted wine, inspecting the cork alone will not determine if the wine has gone bad. Use your other senses. Have you ever had an undrinkable bottle of wine? How did you know it was questionable?