So when you taste a wine that is too sweet, ask for a drier one, or vise versa. If it's too tannic, get a less dark red. Our wines usually don't need to breathe. However, if the tannins are too strong for your taste, you might want to let your wine breathe for awhile. When a wine is breathing, it just means that it is oxidizing.
Reds are the ones that usually breathe.