Milongas: (Argentine Tango) For both ladies and gentlemen, black or dark themes are preferred.
Latin: This refers to venues that specialize in Salsa, Merengue, Cumbia, etc. For gentlemen, any button-up shirt, solid T-shirt or mock turtleneck, dress slacks, and dance shoes. Jackets are nice, but a vest can be even more stylish. Unlike most other dance venues, bright and colorful outfits for gentlemen are acceptable, although dark themes are more common.
Ladies can (and often do) wear sexy outfits: both short skirts and longer slit skirts are popular. Low necklines and exposed midriffs are not uncommon.
(from utdallas.edu (http://www.utdallas.edu/~aria/dance/etiquette.html))