Just what do we mean by a bad smell? And what is the worst smell in the world? The answers depend on culture, age, and personal taste. Westerners find fecal smells repulsive, but the Masai like to dress their hair with cow dung, which gives it an orangey-brown glow and a powerful odor…Though ancient and uncontrollably natural, a fart is generally considered to be repellant, discourteous, and even the smell of the devil. The Merck Manual, in an uncharacteristically entertaining chapter on "Functional Bowel Disease," subheading "Gas," describes the possible origins, treatments of, and miscellaneous symptoms and signs of gas, along with this observation:

Among those who are flatulent, the quantity and frequency of gas passage can reach astounding proportions. One careful study noted a patient with daily flatus frequency as high as 141, including 70 passages in one 4-h period. This symptom, which can cause great psychosocial distress, has been unofficially and humorously described according to its salient characteristics: (1) the "slider" (crowded elevator type), which is released slowly and noiselessly, sometimes with devasting effect; (2) the open sphincter, or "pooh" type, which is said to be of higher temperature and more aromatic; and (3) the staccato or drum-beat type, pleasantly passed in privacy.

While questions of air pollution and degradation of air quality have been raised, no adequate studies have been performed. However, no hazard is likely to those working near open flames, and youngsters have even been known to make a game of expelling gas over a match-flame. Rarely, this usually distressing symptom has been turned to advantage, as with a Frenchman referred to as "Le Pétomane," who became affluent as an effluent performer on the Moulin Rouge stage.

-- Diane Ackerman, A Natural History of the Senses