If you've ever found a bottle of red wine that's been sitting in your kitchen for a couple of months (or years) and taken a smell, you know that red wine can spoil. While wine does not technically spoil the method other food does, direct exposure to heat, oxygen, and sunlight can cause it to deteriorate, giving it an unpleasant taste.
So how does wine spoil? In time, the compounds in white wine that offer it its signature taste and scent break down, and the red wine starts to taste flat and vinegar-y. This process is accelerated by heat and light, so it is essential to store red wine in a cool, dark place.
Interestingly, white wine actually improves with age, approximately a point. As red wine ages, the tannins (substances that offer it a bitter taste) begin to break down and the wine becomes smoother and more intricate. click reference This is why many red white wines enhance with age and why most gewurztraminers are best taken in young.
Nevertheless, once a red wine starts to ruin, there's no going back. Once those tannins have broken down, they're chosen great. So if you discover an old bottle of red wine that's beginning to turn, it's finest to simply pour it down the drain.