Last week my girlfriend Kristal inherited 80 bottles of wine [1]. She invited me over to browse the boxes and taste some of the vintages. The bulk of the wine was from the late '80s and early to mid 90s. While we immediately spotted a couple of valuable bottles, the vast majority were bottles we knew nothing about. Our main concern was finding out if the wine was drinkable. 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. To find out the signs that show 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.
• Avoid red wines that are not Port [2], but have the aroma typically characteristic of Port. When wine tastes like dessert wine, it has been overexposed to heat, and is therefore undrinkable.
• When the cork is pushed out slightly from the bottle, it's a sign the wine has overheated and expanded within the bottle.
• Examine the 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.
• Wine that lacks fruit, is raspy, too astringent, or has a paint-thinner taste is usually bad.
• A still wine that is fizzy or effervescent has undergone a second fermentation after the bottling and shouldn't be enjoyed.
• Although the term "corked" commonly refers to wine that has gone bad, inspecting the cork alone will not determine if the wine is tainted. Be sure to smell and examine the actual liquid.

Have you ever had an undrinkable bottle of wine? How did you know it had turned?