The bow tie is often worn by sharp-dressing Yadas because, according to Doctor Who, "bow ties are cool". A succinct description of the awesomeness of the bow tie is from a NY Times article:
"To its devotees the bow tie suggests iconoclasm of an Old World sort, a fusty adherence to a contrarian point of view. The bow tie hints at intellectualism, real or feigned, and sometimes suggests technical acumen, perhaps because it is so hard to tie. Bow ties are worn by magicians, country doctors, lawyers and professors and by people hoping to look like the above. But perhaps most of all, wearing a bow tie is a way of broadcasting an aggressive lack of concern for what other people think."
The article also stresses the "effete weenie factor" of the bow tie.
Many Yada icons have worn bow ties, including Little Richard, Doctor Who, David Bowie, Tim Curry, Freddie Mercury, George Sand, and Oscar Wilde. Edgar Allan Poe was rarely pictured without one.Origins:
During the 30 Years' War (1618–1648, a.k.a. the War of the Hakkaa päälle), Croatian mercenaries were hired as fighters. These mercenaries typically wore a cotton and silk scarf tied around their necks. These were considered very fashionable by the French, and the style caught on. The French term for it was cravate, meaning, a la Croate. This became the word, "cravat".
After becoming chic in France, the fashion spread throughout Europe. Bohemians were fond of them for some time, and old photos of Kelly Kelly's Bohemian ancestors show bow-tie-clad family members. English people took a fancy to the style as well, and in England, the bow tie seems to add class and distinction to the wearer. Something similar can be seen in the USA.
Formal dinners are often called "Black Tie" and the wearing of a bow tie is required for the male-oriented guests. These exclusive parties would welcome many Yadas and Yada icons.
The bow tie became a Yada trademark in part because Pugnacioun sported one in a photo in which he was also reading The Bibliophile's Dictionary.
C M also mentioned having a bow tie and a tweed jacket.
And although some tie-wearers may opt for the long, dangling tie ("the noose"), a bow tie is more practical—it will not fall in your soup, and if you spill a glass of red wine, port, or other stain-producing victuals, you do not ruin your $80 tie, you just get a spot on your white shirt.