One of the happiest-looking people at the 2008 National Automobile Dealers Assn. convention in San Francisco is a guy manning a booth where gorgeous show models check in.

Whenever I pass by, he’s invariably chatting with tall and beautiful women who register with him en route to their work stations on the exhibition floor.

Their job is to stand around looking stunning, often in provocative dress, as they try to lure dealers to vendors’ exhibits.

That come-hither stuff is done at a lot of conventions, and the NADA models are tame by some standards. Still, the glam gals draw offense from certain quarters.

“You look at the quality of people some vendors are using to attract people, and it’s degrading, insulting,” Tamara Darvish, vice president of the DARCARS Automotive Group, says of the cheesecake approach.

But the guy at the model check-in booth wasn’t complaining.

The NADA convention has a split personality. It is costumed beauties and button-down businessmen, tacky entertainment and deadly serious conferences, cocktail parties and industry workshops, small talk and deep discussions.

Consider the convention’s opening general session. It alternates between circus-like performances and somber speeches.

It begins with an Ed Sullivan impersonator who, in the style of the namesake classic TV show, introduces a juggling act, magician and four musicians imitating the Beatles.

Then 2007 NADA Chairman Dale Willey enters stage left to speak of the need for auto makers to regard dealers as true partners.

He is followed by General Motors CEO Rick Wagoner, who urges dealers to fight regulatory proposals from individual states that want to set their own fuel-economy and emission-control standards.

Then TV talk show host Jay Leno takes the stage to tell jokes. Leno, a car enthusiast, tells dealers, “I love what you guys do.”

Leno isn’t the only car-loving celebrity making a convention appearance. Another one, Ben Stein, speaks at a reception hosted by AutoStar, a financing firm for dealers.

In the movie, “Ferris Bueller’s Day Off,” Stein plays a boring high school teacher who robotically asks, “Anybody? Anybody?” in a hopeless attempt to spur classroom participation.

At NADA, he is animated as he gushes about his love affair with automobiles.

“I’m obsessed with cars,” he says. “The car is the American God. I’m a dream customer who owns seven cars.”

He is poignant (and a bit hyperbolic) as he talks of the empowerment of vehicle ownership.

“A schmuck with a down payment is more powerful than Julius Caesar or Alexander the Great were,” he says. “When you go into a dealership and leave with a car, you are a superstar.

“No other invention in the history of mankind can transform people like that. All because of a machine. But what an incredible machine. Years ago, people said we’d be driving spaceships by now. We do. But they’re called cars.”

He’s just warming up.

“What do you want when you’re young? A car. What do you want when you are middle-aged? A car. What do you want when you are old? A car. It’s the magic of cars.

“My cars are my best friends. For a sip of gas, they do whatever I want. I love them. They are beautiful. I understand why some people want to be buried in their cars.”

And how does he feel about the people who sell those awesome products?

“A car dealer has to be showman, booster, Norman Vincent Peale, psychoanalyst and financier,” says Stein, who in addition to being a Hollywood actor, is a lawyer, economist and financial commentator.

“Car dealers are so fundamental,” he says. “They are the glue that holds communities together.”

Stein is both entertaining and enlightening. In that sense, he’s a good fit for an NADA convention, a multi-faceted event where mood swings are perfectly normal.