Human sweat itself actually has no odor, whatsoever! Rather, the bacteria that feeds on sweat produces a vile smell as a byproduct of its metabolization.

Apocrine glands typically release fluid (perspiration) in response to several factors, including hormones, anxiety or emotional stress. Bacteria found naturally on the skin's surface begin breaking down the protein and fatty acids in the sweat. It's the bacterial breakdown that causes unpleasant smell or odor.

More Info: www.mayoclinic.org