Billy raised an issue or at least alluded to an issue that deserves comment. What to do with leftover wine or wine that is “bad.” I have heard numerous people say something like, “Well, I’ll use it in cooking.” Okay let’s get a grip here and be rational. The quality of your cooking is dependent to a large degree on two things; the quality of the ingredients and the ability of the one preparing them. So here is a culinary axiom for you. No matter who you are—even Charlie Trotter—if you have garbage for ingredients, your talent will only take you so far, and that won’t be too far. Which means ingredients and their quality are important. So if a wine is BAD to drink, it is not going to undergo some mystical transformation when you use it in a recipe or a sauce. So if your wine is truly bad, it is NOT suitable for cooking either! Dump it, give it to your cat, or see if it will remove stains but don’t use it in cooking.
Rule of thumb—I find most red wines will last a good week in the fridge may be even two as far as using it for cooking goes. A wine may not be very palatable to the discriminating palate but is still not “gone.” Go ahead and use it for cooking. White wines may last 2-3 weeks with the same caveats.