In the wrong-headed new film Gigli, the dated notion of fluid sexual “preference” is trotted out by confused Hollywood as trendy, current liberal-think on sexual politics that comes off naïve and antiquated. It doesn't help that it's wrapped up in a soggy and shopworn mob plot that seems to matter less to its star-voltage cast than it does to us.

Larry Gigli (Ben Affleck) is a two-bit, independent thug-for-hire. A reluctant hit man type, whose low-rent boss (grating Lenny Venito) gives him a job - walk into a mental hospital and walk out with mentally challenged Brian (Justin Bartha, overplaying), the brother of a prosecuting attorney trying to put away a New York mob boss (Al Pacino). For some reason, Gigli, though not a relative, is able to waltz into the hospital and waltz right back out with the patient in tow!

After reneging on his promise to take the kid to see a Baywatch shoot (or to a beach to cruise girls, rather), Gigli is surprised to find another hit man at his door (Jennifer Lopez), assigned by the same boss to keep an eye on the proceedings in the likely event Gigli should screw things up. The three quickly settle down together in Gigli's crummy pad for the duration of the film. Of course, the requisite sexual politics hit the fan between Gigli and the new, nameless hit man, to be known as “Lopez” from this point forward.

You see, Lopez is conveniently a “lesbian” - or at least some commercial bastardization of the term, which means that since she's played by Jennifer Lopez and this is a Hollywood movie, she's given carte blanche to wear lipstick, expensive cosmetics, have a great body, designer clothing, three hundred dollar highlights and best of all, to fall in love and sleep with a man, negating her identity as described up to that point. And she enjoys it all to boot, while lying in bed reading Eastern philosophies of peace.

The problems in Gigli are deep-rooted and conceptual. To begin with, Gigli can't even convince us that Lopez is a hit man. A lesbian is an even bigger stretch. I'm all for the idea of fluid sexuality, the Kinsey scale, experimentation and all things not being “black and white,” as overstated in the film by Lainie Kazan in an embarrassingly broad though somewhat effective cameo.

But the notion that a gay person is such simply because they haven't experienced the right member of the opposite sex is an insult to what we know today about gender, sexual orientation and Will and Grace.

Sorry Gigli, sexual orientation ain't a matter of flip-floppin' whichever way the wind blows on any given day. And given that Larry Gigli is such a dumb and unpolished character, obviously of little intelligence or finesse, what's the reason Lopez has found in him what other men didn't have, as she explains?

There are some crassly effective scenes that are watchable enough even though they espouse some dated, superficial takes on issues of gay and straight, male and female form, attractions and revulsions, all while Lopez moons at Affleck then talks out of the other side of her mouth over her disinterest in men.

The one “real” lesbian character is Lopez' ex-girlfriend - a shrill, man-hating psycho who attempts violent suicide onscreen to win Lopez' affections back. In their big confrontation scene, they seem more like bickering sorority sisters than lovers at the end of the road. It's all play-acting, put on, safety-zone fun and games, because at the end of the day, Lopez and Gigli do sleep in the same bed.

Gigli has been written from a perspective of complete superficiality, and pales in comparison to a similar-themed film of recent years, the wonderful Chasing Amy.

Chasing Amy, if you remember, was Kevin Smith's disarming, raunchy and politically incorrect, comedic take on what happens when an off-beat, heterosexual cartoonist (also played by Affleck) falls for a gorgeous lesbian cartoonist, played by doll-voiced Joey Lauren Adams. As in Gigli, they do end up having an affair and the lesbian's motivations are questionable.

But at least Chasing Amy had the guts to pursue its relationship to its logical and unhappy ending, with a great degree of heart and smarts - maybe even passion. Gigli, on the other hand, is a pallid take on the same issue, trumped up with less complexity than an episode of Ellen.

By now it's no surprise that Ben and Jen met and fell in love on the set. What is surprising is how little chemistry they show together onscreen. They seem to be acting in different zones, with Affleck using a hammy, condescending accent to convey his superiority to Larry Gigli, which is mannered and flies directly in the face of Lopez' more natural and appealing, low-key vibe. Say what you will about J-Lo, she's easy on the eyes and it's clear in Gigli that she's got a sly, underplayed charm that's not hard to warm up to. Her performance and lack of show-offiness in the role may be the best thing in the film.

The most annoying member of the cast is Justin Bartha as the retarded (politically incorrect, I know, but seems befitting in this case) Brian. Gigli mistakenly assumes that we're going to develop some empathy towards him simply because he's mentally challenged. His performance grows grating quickly, and by the end of the film we can't wait to get him off the screen.

Why would the usually competent writer-director Martin Brest write this crap, and why did such top-flight actors as Lopez and Affleck think that it was funny or worth saying?

On the positive side, the film comes alive only briefly in a few broad cameos involving Christopher Walken, Kazan and Al Pacino (these days making a career out of bellowing to the rafters). There's also a pleasant acoustic-guitar theme that runs sweetly throughout the film.

The conclusion of the film involves an endless scene that plays like an absurd homage to all things Baywatch and Rainman, with the insufferable Brian frolicking around in a personal victory we couldn't care less about. And of course, there's a note of focus-group driven optimism that the mismatched “lovers” may actually have a future together, with Ben and J-Lo gazing wistfully into each other's eyes.

Go back and compare the look on Joey Lauren Adams' face in the melancholy last scene of Chasing Amy to Lopez' hopeful expression here, and you've got a world of difference between something incisive and something insipid.