Have you ever noticed that an acute sense of smell and bad breath don't seem to come together in the same person? That is, people with halitosis often breathe right in your face without making any effort to conceal or divert the odor - they don't seem to know it's there. In fact, when someone asks you anxiously whether their breath is bad, it usually isn't. How can we explain this paradox?

Many people have noted that when it comes to our own breath smell is unreliable. We seem incapable of detecting an unpleasant odor coming from our own mouths, probably because the nose is constantly bathed in the smell from the mouth and more or less cancels it out: a large part of taste is smell, generated by food odors traveling up the back of the oral cavity to receptors in the back of the nose when we have food in our mouths. Our own body smell and bad breath odor seem normal to us.

It seems that the best way to connect smell and bad breath is to get someone else to make the judgment. The family physician may be the best person to ask because your dignity will suffer less and you are more likely to get a really honest answer. If this isn't an option, select a really good friend - one who you trust to be honest, sensible, and impartial - and ask them to judge your breath odor. Make sure that you don't do anything ahead of time to make your breath smell different from usual: avoid coffee, alcohol, strong flavored foods, tobacco, breath fresheners, and anything else you think might affect the experiment. You don't want to hear, "I can't tell the difference between the cheese smell and bad breath!"

There is one way you may be able to judge your own breath smell if you really can't get help from anyone else. Simply lick the inside of your wrist and then sniff your wrist. If your wrist smells bad to you, your breath probably smells that way to others. Before you do this, consider the same precautions as if you were having a friend sniff your breath: your wrist should be clean (no perfume, scented body lotion, or anything else that might affect your sense of smell and bad breath detection) and again, don't eat anything that might change the odor of your breath at that moment. Be aware, also, of odors in the environment that might affect your smell test.