Sacha Baron Cohen stars as the titular character in “Brüno.”

“Brüno,” Sacha Baron Cohen’s shock-and-ach du lieber follow-up to “Borat,” is a miss-or-hit mockmentary aimed at turning another of his “Ali G Show” guises into a pop cultural phenomenon.

But “Borat” was such a hit that it’s a struggle to find people gullible enough to not recognize the star. And in many “bits” developed for this gay Austrian fashionista’s assault on Fashion Week in Milan, the Middle East, clueless cogs in LA’s dream machine and rural America’s rube-eoisie, the strain shows.

The conceit here is that Bruno is host of “Funkyzeit Mit Brüno,” a trend-setting Austrian fashion show that plays like a “Saturday Night Live” “Sprockets” tribute.

Brüno craves fame. He wants to be “the biggest Austrian superstar since Hitler.” But when his TV show is canceled after a backstage fashion show debacle (a worthy target), he loses his lover, Diesel, and his direction. How can he become famous now?

Maybe by making peace in the Middle East — traipsing around Jerusalem in Hasidic short shorts (Hasidic Jews chase him). Perhaps an “accessory” African baby adoption (a “gayby”) is the answer — watch passengers’ jaws drop when the infant is collected from a box in the airport luggage carousel.

Or maybe, if he wants to become “the biggest gay movie star since Schwarzenegger,” he needs to emulate such stars as “Tom Cruise, John Travolta and Kevin Spacey.” The secret is being straight. Can Brüno “change?” Naturally, he goes to Alabama for church counseling, infiltrates a National Guard base for Officer’s Candidate School and heads out hunting with “the boys” for a few butch lessons.

And no, you don’t want to know what a “swinger’s club” in rural Alabama looks like. But Bruno does.

The targets seem more hapless this time — Paula Abdul shows up for an interview and Brüno has her sit on Hispanic hired help. Presidential hopeful Ron Paul bails out of a chat the moment Brüno starts stripping. A “terrorist” leader in Lebanon gives him the boot when Brüno comments on “King Osama’s dirty wizard” beard. Few people worth mocking are fooled by the disguise any more.

By the time we visit a Texas TV show to watch him enrage a crowd of “Maury”-“Jerry Springer” show stereotypes (black and obese) with his adoption of the African baby he’s given “a traditional African-American name — O.J.,” the groans outnumber the giggles.

Baron Cohen and his partner in ambush-interviewing, Larry Charles of “Borat” and “Religulous,” seem to have a taste for the twisted and juvenile view of gay sex, all kinky appliances and gerbil jokes. They want to mock homophobia but do it by getting into people’s faces with comical fetishism.

There’s a love story between the star and his adoring assistant (Gustaf Hammarsten) that doesn’t play, but does show off their command of German and Hammarsten’s willingness to go just as far as Baron Cohen, when the chips are down.

The better bits are the “Ali G”-ish chats with quarreling Middle East factions.

“Isn’t pita bread the real enemy?”

“You’re confusing Hamas with hummus. We both like hummus … It’s very healthy.”

There are plenty of laughs, a few of them explosive. Baron Cohen’s determination to let uncomfortable pauses and the unblinking camera get under the veneer of civility of his subjects can be hilarious.

But too often, “Brüno” feels like “Borat’s” weak-wristed brother, too much of it just a gay cliche aimed straight at the American bigot belt. An elaborate set-up with fans of blood-sport “cage-matches” can seem both brave and pathetic. These aren’t the best and the brightest that we’re laughing at here.

We could fret over all the movies Sacha Baron Cohen could have followed “Borat” and “Sweeney Todd” with, but at least “Brüno” closes the book on this part of his career. At this point, there’s nobody worth fooling who still will be fooled by his shtick.