The tribute to the late Bernie Mac that appears during the closing credits to this movie—it includes outtakes, behind-the-scenes footage, bits of his standup routines, and excerpts from interviews with him—makes “Soul Men” an even more dispiriting experience. It’s sad to think that so crude and unfunny a picture could be the swan song of such a likable, talented man.

The script takes as its premise a sort of R&B version of Neil Simon’s “The Sunshine Boys.” Mac and Samuel L. Jackson play Floyd Henderson and Louis Hinds, former backup singers for Marcus Hooks (John Legend), who tried to form a duo after he left for a solo career but split up acrimoniously over a woman both loved. Floyd went on to become a successful car wash impresario, now unhappily retired, but Louis slipped into crime and post-prison penury.

When Marcus, who became a huge star on his own, suddenly dies, the boys are invited by promoter Danny Epstein (Sean Hayes) to reunite to sing in a memorial service being planned at Harlem’s famous Apollo Theatre, which will be televised on VH1. It’s something Floyd wants to do despite surly Louis’ initial refusal. Finally they overcome their differences enough to begin the long drive from Los Angeles to the Big Apple—since Louis, for no reason other than to turn the picture into a road movie, won’t fly.

What follows is a series of picaresque episodes in which the boys rehearse their long-dormant act in crummy venues along the way while stopping in Tulsa to save Cleo (Sharon Leal), the daughter of the woman they jointly loved (and perhaps the daughter of one of them) from her abusive boyfriend Lester (Affion Crockett) and take her along with them. They also have to contend with an intern from Epstein’s office named Philip (Adam Herschman), a plump, bushy-haired nerd who’s one of their biggest fans and bails them out when they need cash or get into inevitable trouble with the law. Lester also reappears to threaten everybody before the guys predictably triumph at the Apollo.

Jackson and Mac promise so much as these two cantankerous old codgers that it’s especially pathetic to see their interaction reduced to little more than a series of foul-mouthed screaming matches, clumsily choreographed slapstick physical altercations and lecherous trysts with grossly unattractive women. Some solace is offered in the musical numbers, in which they seem to be having a roaring good time, but the constant waist-down cutaways during the elaborate dance moves are a constant giveaway that they’re not actually doing the more elaborate moves, and the impact pales on repetition.

Worse, all the stuff involving Herschman and Crockett is dismal—and there’s a lot of it. The former is supposed to be a lovable dweeb and the latter a comically inept would-be gangsta, but both come across as insufferable, especially the sleepy-eyed Herschman, who’s given a scene in undies that will definitely make you want to close your eyes. By contrast Hayes and Leal are merely bland. So are the listless direction by Malcolm D. Lee, the colorful but chintzy physical production and Matt Leonetti’s characterless cinematography.

“Soul Men” also includes a cameo by the late Isaac Hayes, who frankly looks awful in his few moments toward the close—far worse than Mac. But it’s the latter about whom one’s likely to feel the most queasiness, especially in the opening scene in which he’s dropped off at the retirement community by Duane (Mike Epps), the nephew who’s taken over his business, and the unhappy Floyd refers to the place as a “death camp.” (A later sequence where he contemplates suicide also has an unpleasant taste to it.)

Apart from the real-life overtones that sour “Soul Men,” however, it’s the quality of the material itself that’s terribly depressing. Mac was a wonderfully funny man, and Jackson was obviously juiced up by working with him. But the coarseness of the script and the mediocrity of its execution sabotage them both, making the picture less fitting tribute than major disappointment.