I once went to a flamenco class taught by a middle-aged Irishman. He was a good teacher, but I never got on with all that complicated footwork. One night I went to see him perform with his students. He came on to introduce the programme and I was startled to hear him speak in a cod Spanish accent. I'm afraid it was the end for me and I never went back to the class after that.

Why his pretence at being Spanish should have so disillusioned me I don't really know; I wasn't put off by the spotted frocks, fixed frowns and false fury of his dancers. I even half-expected these, for stereotypes have a big profile on the multicultural dance scene. They're a kind of fancy dress for the soul, and there's nothing wrong with a bit of dance therapy. Besides, you can just as easily find yourself confronting the cliches of flamenco when watching professional dancers in Spain. Coming across real flamenco is, by definition, rare. Essentially a spontaneous, improvisatory art, performers themselves describe flamenco as being all about living for - and expressing - the feelings of the moment.

Over the years I've seen all kinds of flamenco. I've sat in a cave in the hills above the Alhambra, sipping watery sangria while a couple of sulky teenagers twirled their arms listlessly above their heads. I've listened to flamenco outside a cafe in Cordoba, which ended up with the two guitarists fighting in an adjoining alley over their takings. And I've seen wonderful, fun flamenco. Like the show I caught in a basement tablao in Seville on a tiny, rickety stage. The singer had a mane of blonde hair and wore a red dress bursting at the seams. I believe she was called something like "The Golden One". She marched to the front, thrusting her bosom forward and harangued us in song. At the end of every verse she tossed her hair, turned on her heel and marched to the back of the stage (all of three paces) singing: "I'm off! I'm off to start a new life!" Once, she turned her back, pulled her skirt tight round her bottom and wiggled it, and the men in the audience shouted and stomped.

Intimate, smoky tablaos work perfectly for flamenco, which belongs in bars and round camp fires, not on raised stages for rows of people hidden in the dark. Flamenco companies trying to establish an international reputation have a tough time of it, creating work that fits the formal demands of theatre, and an even tougher job pleasing the dance establishment. JoaquIn Cortes tried hard, fusing flamenco with contemporary dance and music. But when he swaggered up the aisle of the Royal Albert Hall bare-chested, wearing a kind of upmarket sarong, all he got for his pains was the barbarians in the press howling "A man in a skirt!".

Female performers, meanwhile, have to contend with the merciless scrutiny of critics who like their dancers young and slim. Back in the 19th century they preferred women with embonpoint. Those were the days when "the meat in the seat" (as they called it) and a shelf of bosom were indices of beauty, and one Spanish dancer was praised for having arms "so beautiful they resemble two sausages hung in the kitchen in winter".

Not any more. "Too willing an addiction to paella is much in evidence," wrote one London critic sniffily of a visiting flamenco company, and went on to describe them as "God's gift to the corset industry". One of his colleagues tiptoed round their star performer with the words, "She is, shall we say, somewhat advanced in years".

But flamenco enthusiasts and amateur dancers who turn out in encouraging numbers to theatres such as Sadler's Wells to see their favourite performers are not looking for chorus lines of slim, pale young dancers. They don't want black and grey and wet and dreary. They want red and gold and grand emotion. They want to indulge the gypsy in their soul, and flamenco is the dance that appeals to the mad romantic in all of us.

Some people can't see the point of flamenco. For the English, all that over-the-top emoting can be horribly embarrassing. I once suggested to someone who couldn't understand its appeal that the popularity of dances such as flamenco is down to our not having a national dance of our own. "Yes, we do," he argued, "we have morris dancing." Well, I said, I mean a dance with passion, sensuality. "There's plenty of passion in morris dancing," he snapped. What can you say to that?

Until recently the Spanish, too, held this immigrant art at arm's length, because of what many regarded as its grubby, rather than romantic, gypsy connections. Then, suddenly aware of the profile it was acquiring on the international dance scene, as well as its tourist potential, they decided to adopt it as their alternative national dance. Now, like social dances in many other cultures, it's there on all the postcards, promoting an image of Spanish fire and passion.

Sadler's Wells is hosting a two-week flamenco festival in February, including performances from some of the best contemporary artists in Spain: the singer Jose Merce, leading Seville-based dancer Maria Pages and the 20-year-old star Farruquito (following in the flamboyant footsteps of his grandfather El Farruco, a legendary Flamenco dancer and founder of a school).

But contrary to what many people assume, Flamenco is not Spanish in origin. Indeed, it is an art so mired in confusion that where it comes from and even its name are the subject of debate. According to Spanish dictionaries, it derives from a word meaning "coarse and flippant". Another fanciful idea is that "flamenco" became attached to the dance because certain of its positions recalled the flamingo bird. A more plausible belief is that its name refers back to the art's origins and comes from the Arabic for "fugitive peasant" (felag and mengu).

Part of the confusion surrounding flamenco is that, even though it evolved in Spain, it's really an exotic plant. It grew out of Indian, Jewish and Arab roots, a product of the immigrant experience, and lodged itself in the gypsy community where it acquired, for outsiders, all the romantic allure of gypsy life.

But while most people find the exotic appealing at a distance, it is a different story close up. Men in skirts? Arms like sausages? A dancer strutting about on stage in her sixties? Some years ago, I performed in Sadler's Wells's small Lilian Baylis Theatre at the same time as a flamenco company was occupying the main house. One afternoon in the cafe upstairs I found myself having a coffee with one of the show's star performers. She must have been at least in her sixties then. She had half her teeth missing, was smoking like a chimney and had the body of a woman who clearly enjoyed her food. But she was a demon on stage! I said I thought it was amazing that she was still performing at her age. Her eyes glinted dangerously as she looked at me. "Let me tell you a secret, my dear," she said, leaning across the table. "When you dance, there is no such thing as old age."

Flamenco Festival London runs from 5-17 February at Sadler's Wells Theatre, London EC1 (020 7863 8000)

Wendy Buonaventura's I Put A Spell On You: dancing women from Salome to Madonna is published by Saqi Books