Three new movies celebrate Las Vegas. In Showgirls, one of the cast is listed as "casino lecher". (I know someone who could have played that role pretty well: but they didn't give me an audition.) Showgirls has been panned as a sordid, schlocky soft-porn movie. True, but it does contain a lot of truth about Las Vegas, the seamy side, where sex is just another number on the board.

The film, in an awful way, contrives to give you more of Las Vegas than the much-hyped movie Casino, which opens in London this month. The first hour or so of Casino (nearly three hours in all, but it seems like a week) is in effect a tutorial on how a casino is run. Or was run in the 1970s.

At that time, one of the nastiest gangsters who ever lived, Tony "the Ant" Spilotro, so called because of his diminutive stature, terrorised the whole town. He was the strong-arm man for the Chicago family, which was skimming the Stardust for many millions a year. Their front man was Frank "Lefty" Rosenthal, a soft-soaping fixer and odds-maker. In Casino, Scorsese does for violence what Showgirls tries for sex. In the end, Spilotro was bludgeoned to death in a cornfield, Rosenthal was blown up in his car, but survived, and he kept his mouth shut.

As a picture of the good fellas' way of life, Casino offers rather less than meets the eye. The reason is that, at heart, the story is not really involved in casino gambling, or explaining why 24 million people a year go to Las Vegas. It is hooked on a technicolor version of adultery, in which Tony the Ant breaks the mafia's first commandment: "Thou shall not covet thy fellow mobster's wife."

Leaving Las Vegas, the third new movie about the town, is not about sex or violence: it's all about drinking. The gambling is marginal, with Vegas merely a backdrop. There is one gambling scene at the dice table, red cubes flying through the air, which is brilliantly shot. The best line about Las Vegas in these new movies comes from Showgirls. "Good luck! That's what they always say in Vegas before they take your money."