First of all, a certain amount of bad breath (or halitosis, if you want to get technical) is unavoidable. When you first wake up in the morning, or after you eat a tuna salad sandwich, you’re going to have bad breath. However, if your bad breath goes beyond what’s normal, and no amount of teeth-brushing can eradicate it, then you may be doing some things that are unintentionally causing your oral odor. The good news is, once you've determined the source of your bad breath, it's usually a very easy problem to fix. So if your breath has been off lately and you’re not sure why, then read on — one of these seven possible causes is probably the culprit.