Like many contemporary movie stars, Jennifer Lopez has been the object of tabloid scrutiny and speculation having little to do with her work. But breathless gossip shares column space with weekend box-office grosses nowadays, and Ms. Lopez achieved perfect negative public image synergy when she co-starred with her then-beau, Ben Affleck, in “Gigli,” a paradigmatic bomb greeted with critical scorn and shrugs from the ticket buying public.

But the former not-quite Mrs. Affleck’s cachet and magnetism have endured. Ms. Lopez, who was so earnest and winning as “Selena,” and so cheerfully kicked butt in “Anaconda,” survived “Gigli” and has gone on to regularly beat Sandra Bullock to romantic comedy fans’ easy-opening wallets with “The Wedding Planner,” “Monster in Law,” and “Maid in Manhattan.”

Ms. Lopez’s new film, “El Cantante,” is so jumbled, dark, and directionless, that it almost seems to have been intended as an antidote to the energetic and lightweight formula fluff that pays the actress’s bills. Tabloid logic suggests that the “Gigli” curse has again risen to torment J-Lo, since “El Cantante” pairs her with an offscreen significant other.

But to blame her co-star and real life husband, Marc Anthony, for this woeful tangle of rock ‘n’ roll clichés, stagnant dramatic confrontations, and highly suspect music history, would be to kill the messenger. Mr. Anthony’s portrayal of Hector Lavoe, the star-crossed Jim Morrison of salsa music, whose Roman-candle life sputtered out at age 46 due to complications from AIDS, accounts for most, if not all, of the film’s highlights.

Lavoe had a wife, Puchi, played by Ms. Lopez, and neither “El Cantante” nor Ms. Lopez’s character lets the audience or anyone in the story forget it for a second. When we meet Puchi, she is grudgingly sitting for a fictionalized documentary crew a decade after her husband’s death in 1993. When we meet Lavoe, it’s the early 1960s and he is still Hector Perez, a skinny and likable young Puerto Rican singer eager to follow in his brother’s footsteps by immigrating to New York.

Hector’s musician father (Ismael Miranda) is worried that the boy will take the additional steps to a fatal overdose like the one that killed Hector’s brother, and he refuses to condone his son’s ambition. In New York, 17-year-old Hector quickly conquers the city’s electric Afro-Cuban music club scene with the help of the emerging flagship label of salsa music, Fania Records, and band leader Willie Colon (John Ortiz).

Hector, rechristened “Lavoe” by the suits at Fania, also falls in with two highly problematic muses: the heroin needle, the means by which he eventually contracts AIDS, and Puchi, whom he marries in a stupor after she gives birth to their child. “El Cantante” was developed and produced by Ms. Lopez’s production company, so it shouldn’t be a surprise that she is front and center for most of the film’s 116 minutes.

The script feasts on Puchi’s apparent charmlessness to an almost pathological degree. Each of Puchi’s many determinedly grating fits of codependent petulance and rage directed at Lavoe, Colon, the record company, or anyone else within scolding or cajoling distance, is an indelible sign that the film’s creative brain trust was asleep at the conceptual wheel from the script stage on.

Another director might have attempted to subvert Hollywood logic and audience expectations by turning “El Cantante” into a pure and biblically brutal portrait (like Martin Scorsese’s “Raging Bull”) or a razor-sharp narrative carve-up (like Michael Winterbottom’s “24 Hour Party People”). Instead, director Leon Ichaso is content to go with the late-’90s cable-movie stylistic flow by alternating cluttered two-shots and close-ups dominated by Ms. Lopez’s pouting profile with rushed exchanges of toneless dialogue, fake flash frames, and explanatory headlines.

The film’s music sequences are buoyed considerably by Mr. Anthony’s exuberant take on Lavoe’s masterful stage presence and infectious repertoire, but unfortunately, almost no song is performed to completion. Drifting onscreen lyric translations inadvertently suggest a commercial for Cialis as much as they effectively unpack the passion and poetry of Lavoe’s music.

In a post-“Ray” and “Walk the Line” world, faulting a music biopic for playing fast and loose with history is a waste of ink. But the light skim through the facts of Lavoe’s life in “El Cantante” is particularly frustrating considering how little dramatic momentum the filmmakers are able to muster. Lavoe’s first child by another woman doesn’t warrant a mention. The announcement of Lavoe’s mother’s shattering death is trotted out well past the halfway mark. A “eureka moment” scene, in which Fania executives, Colon, and Lavoe coin the term “salsa” to describe their mixture of tropicale music styles, is about as accurate as a scene depicting Elvis and Colonel Tom Parker pulling the phrase “rock ‘n’ roll” out of thin air would be in an Presley biopic.

Though positioned as a breakthrough celebration of one of the giants of Caribbean music and Puerto Rican pop culture, “El Cantante” is a timid superficial sheep of a showbiz biopic in flashy nonlinear narrative wolves’ clothing. Hector Lavoe was a one-in-a-million performer who witnessed and initiated enough tragedy for a dozen men. But to quote “La Voz’s” exasperated wife in a scene in which she’s summoned to a heroin-shooting gallery to pick up and dust off her spouse, “El Cantante” is just “the same old f—ing story.”