We’ve never known quite what to think about Franz Liszt. Yes, he was a staggering virtuoso pianist, probably the greatest who ever lived. Yes, he was a giant figure of the Romantic age, and during his touring years in the 1830s could claim to be the most famous man in Europe. Yes, there are a handful of pieces among his 700 or so works where he surpasses himself and creates something on the level of Chopin, or even Beethoven.

But then there are the far more numerous pieces stuffed with glissandos and impressive leaps, but no actual music content, like the notorious Hungarian Rhapsody No. 10. Plus, there are those other aspects of Liszt that make the serious music-lover’s nostrils twitch in disdain.

All that flamboyant womanising, which continued even after he’d become a Catholic priest and wrote letters about his yearning for the simple life, while travelling thousands of miles a year. All that pretending to be a great Hungarian patriot, while not speaking a word of the language. All that absurd acting out of the masterful, erotically irresistible virtuoso: striding across the concert platform, the Hungarian sword of St Stephen clanking at his side, then peeling off his gloves, with one eye on the ladies, who sometimes swooned in ecstasy.

For anyone who feels that sincerity is the touchstone of great art, Liszt simply isn’t going to pass muster. With Liszt you often get the sense that a piece of music is simply the launch pad for extravagant feats of pianistic fireworks, draped over the chaste outlines of the music like lipstick daubed on a Madonna.

Liszt himself was aware of this tendency. In later life he tried to justify it by saying that when he was young he wanted to reach out to musically illiterate people, to get them to see the virtues of Bach or Beethoven, and to do that it helped to sauce their music up a little.

I don’t believe a word of it, and that’s not because I join with the sneerers who say Liszt is never sincere. I don’t believe it because I don’t think Liszt believed it himself; he’s just trying to cover his tracks. Look at the evidence of his music and you find that the neat distinctions between sincerity and showmanship simply melt away. He understood that music-making is always an inextricable blend of these two things. As he put it himself, performance and composition are all about “very cleverly steering a course between the Ideal and the Real”, meaning if you want to give people a glimpse of the transcendent, you need to excite and titillate them first.

That might seem like pure cynicism, but there has never been a less cynical composer than Franz Liszt. On the contrary, he was chock-full of idealism, hence his need to do good works. For a while he was an ardent follower of the social reformer Saint-Simon, and then became a no less fervent believer in the democratic, tender-hearted vision of Catholicism held out by the Abbé de Lamennais.

Underlying Liszt’s fervent idealism was an enormous fund of good-nature and generosity. He helped innumerable composers while director of music at the Weimar Court, including Wagner, and made remarkably faithful piano transcriptions of Beethoven symphonies and other canonical works, as a way of bringing music to the toiling masses. On top of all this, he was well-read, sensitive to the visual arts and nature, much travelled, impressively polyglot, and curious about other people. I can’t think of any great composer I’d rather have dinner with.

Ah yes, but what about the music? When all’s said and done isn’t it still often vulgar? I would say yes, but it’s none the worse for that. Some people try to rescue Liszt from the charge of vulgarity by singling out those strange gaunt masterpieces of the composer’s old age. In pieces like the haunted, sad At the Grave of Richard Wagner Liszt finally turns his back on virtuosity and peers into the heart of modernist darkness. This is the “real” Liszt, they say, purged of his embarrassing virtuoso excesses.

To me, this is just snobbery. These late works are no more the “real” Liszt than the entertaining Grand Galop Chromatique, or the well-known Hungarian Rhapsody No. 2 that worked its way into popular culture and was satirised in a Tom and Jerry cartoon, or the stupendous B minor sonata, or the Faust Symphony. In fact, I would say they are less so because they lack the exhilaration in virtuosity that is an essential part of Liszt’s fascination. Someone who understands this better than anyone is the Australian pianist Leslie Howard, the only musician who has ever recorded every note that Liszt wrote for the piano. Tomorrow, he’ll be playing a 75th birthday recital which reveals every side of Liszt’s genius. Relax your scruples and go.