I can't help but quote Alan Booth on this:

Geishas, the coffee-table books and up-market glossies and thoughtful TV documentaries never tire of telling us, have no truck whatever with crude fleshly pleasures. They are highly skilled entertainers who specialize in shamisen ballads, exquisite dances, elegant repartee, party games with matchsticks, and delicate liaisons with incumbent prime ministers. To confuse them with women who grant sexual favors to lesser mortals for money is to be as ignorant and misinformed as were the occupying American GIs who, shortly after their arrival in 1945, are said to have congregated on the Ginza and set up cries of "We want geesha girls!" Imagine the indignation of the local populace! Why, these barbarians wouldn't know a skilled shamisen performer from a hula dancer! Oh woe, the coarseness of foreign education! And then, to smooth ruffled national pride, the more affluent among the populace likely took themselves off to a hot spring for a bath, a drink, and a fuck.

-- Alan Booth, Looking for the Lost

I think the real misconception is in how geisha are viewed in the West: no, not as prostitutes, but as bizarre sexless substitutes for prostitutes. According to this view, the inscrutable Japanese don't even need sex, but instead they satisfy themselves simply through the esthetic pleasure of watching geisha pluck cat gut and croon folk songs. How wonderfully civilized! Even better yet, these life-sized dolls are cultivated like bonsai trees, to such an extent that their beauty and their skills cannot even be fully appreciated without a thorough indoctrination in the Japanese Way. Why, oh why, can't we in the West emulate such exquisite tastes and strength of character? The idolization of seppuku/harakiri, with characters in James Clavell novels like Shogun disemboweling themselves without even a grunt while composing poetry, is much along the same lines. Behold the Wonders of Japan!

This is not just bullshit, it borders on offensive, and nearly every book about Japan written by Japanese writers either laments or snickers about such absurdity. Fact is, onsen geisha (hot spring prostitutes) and their ilk have always way outnumbered so-called "real" geisha. The sex industry in Japan is huge, and it has been huge for as long as there have been records of it (cf. Yoshiwara). And why not? Human nature means it's pleasurable to get laid, and Japanese morality doesn't proclaim extramarital or commercial sex to be a sin. Even at worst, if exposed to others, it's only shameful (hazukashii). Geisha who do not engage in hanky-panky may exist, and even more may at first claim so in order to drive up their price, but they're about as common as asexual escorts.

Although I have to add one caveat: the Western view has become so ubiquitous that it is starting to affect the geisha themselves. These days, the average age of geisha is pushing sixty, and many make their living posing on stage in fronts of crowds of googly-eyed foreign tourists, acting out what they expect to see. In Kyoto, the largest geisha center, there are less than 200 geisha left. Like kabuki and the tea ceremony, geisha have minimal relevance to the vast majority of the Japanese populace, and even those remnants are rapidly disappearing -- it's just sad that their last days will be spent as a freak show for tourists.