The Bolshoi's Spartacus is one of those ballets which is so bad that it's great. Actually, I revise that: Spartacus is one of a kind.

Laden with its Soviet baggage, Yuri Grigorovich's blockbuster of 1968 discomfitingly weds soapbox to art, the USSR's might with the personality of the Bolshoi Ballet. Watch those brutal stomping Roman soldiers and those heroic underdog gladiators, and one can well imagine an entire people being whipped up to shout against the vile imperialist West.

Now its entire context has gone. Communism is disgraced, and blockbuster entertainment is the province of Hollywood. Fascinating then to see the Bolshoi reprising a ballet that a few years ago they were minded to drop, so inextricable did it seem from an uneasy past.

Even more fascinating that the changing times, far from subverting Spartacus, seem quite remarkably to heighten its brilliant, base theatrical power. The serious motifs remain, but they slip painlessly into contrary values; now it's as if Emperor Crassus and his iron-clad guards are the Stalinist tyrants and the gladiators are the men of freedom.

And its ballet style - macho for men, flowery for women - is as slickly gratifying in today's unisex dance world as a cake to a cabbage-soup dieter.

Spartacus has become a striking art-political cartoon, satirising politics, the public's manipulability, and even ballet itself.

From my plush seat in the home of Ashton and MacMillan's beautiful ballet-theatre of truth and subtlety, I found all objections to Grigorovich's work - that there isn't a single truthful emotion here, not a shred of individual sensitivity or reality, only a choreographer's stereotypes - slip away, lulled and neutered by the visceral impact of watching goose-stepping villains, windflower women, and an all-man hero, who, despite his shackles, tears defiantly through the air faster, higher and longer than ever seen before or since in a male ballet role.

Simon Virsaladze's costumes help a lot in the viewer-seduction process - men in very short metal skirts and high calf-guards, slim-thighed women in even shorter tunics, with yards of brown leg everywhere. His sets also help you focus on the flesh - a brutalist colonnade alternating with a swooping mesh screen.

Aram Khatchaturian's barnstorming score sweeps along without pause, throbbing with violins to undam our emotions, bashing our ears with drums to whirl the passions into action.

His purple chutzpah is matched every step by Grigorovich's choreography - acrobatic love duets, vulgar pole-dancing orgies, bloodfiring male ensembles, a few dull bits, but most of it eye-watering.

Grigorovich claims his character drawing to be of revolutionary psychological depth, but their laughable simplicity proves more durable. Straw-haired Dmitri Belogolovtsev exudes forceful charisma and a vehement honesty as Spartacus, even if he can't quite match memories of Irek Mukhamedov's magnificence in those groin-cracking jumps.

Vladimir Neporozhny's long-legged Crassus has an interesting weakling streak. Galina Stepanenko's likeably brassy courtesan Aegina started well but lacked the coiled allure of the injured Nadezhda Gracheva, whom she replaced. As Spartacus's pure wife, Anna Antonicheva looked thin and underpowered, which had a sort of pathos.

It's a ballet that sums up the Bolshoi uniquely and unforgettably, and they wear it like a badge of honour.