Urban legends, old wives' tales and myths surround nearly everything, and bad breath is hardly an exception. The amount of information (and misinformation) out there about halitosis is nearly unfathomable, so occasionally it helps to take look in a book, as they say on Reading Rainbow.
Be careful, though. In the text Myth Information, by J. Allen Varasdi, you can find "bad breath" listed between "bacteria" and "bagpipe." The author notes that oral odor can be caused by poor dental health, gingivitis, mouth infections or tooth decay, but that, for the most part, it is not caused by bacteria.
Many oral health experts disagree! While Varasdi believes that halitosis starts in the lungs, most physicians and dentists say that it is generally an oral problem. In Larry Frieders' The Undruggist: A Tale of Modern Apothecary and Wellness, for instance, bad breath is chalked up to bacterial growth.
Studies generally uphold the latter idea. While halitosis can come from the lungs, it almost always originates in the mouth. Using a specialty breath freshener or an oral care probiotics kit, like the Aktiv K-12 system, may help sweeten your breath.