Those who go to “Sabotage” expecting an enjoyably old-fashioned Arnold Schwarzenegger vehicle will be very unpleasantly surprised, though the fact that it was co-written and directed by David Ayer (who wrote “Training Day” and both wrote and directed “End of Watch”) should serve as a forewarning. Like his previous pictures this is a grim, blood-soaked, very ugly exercise in mayhem and macho action, in which the Governator broods sullenly throughout. It’s one of those movies you come out of feeling the need for a shower—and not because you’ve been sweating with excitement.

Schwarzenegger plays John “Breacher” Wharton, the head of a DEA Special Ops team composed of agents so buffed up and grubby looking that they can go undercover on the seamiest missions. Among the crew are James “Monster” Murray (Sam Worthington) and his wacked-out, spitfire wife Lizzy (Mireille Enos); Joe “Grinder” Phillips (Joe Manganiello); Eddie “Neck” Jordan (Josh Holloway); Julius “Sugar” Edmonds (Terrence Howard); Tom “Pyro” Roberts (Max Martini); Bryce “Tripod” McNeely (Kevin Vance); and “Smoke” Jennings (Mark Schlegel). The lucky ones in this collection are Enos, the only woman, Howard, the sole African-American, and Worthington, who gets to sport a goatee that at least distinguishes him from the other guys, who all seem pretty interchangeable in their hard-ass biker gear. But on the other hand it’s doubtful one would particularly want to be recognizable in this context.

Anyway, we don’t get to know Jennings at all because he’s literally smoked in the opening sequence, a bloody incursion into a cartel-controlled mansion that the team uses as a diversion for them to swipe a sizable portion of the cash on hand even as their boss Demel (Martin Donovan) watches from afar before blowing up the remainder to conceal the theft. That prologue introduces what become Ayer’s motifs for the rest of the picture. First, there’s lots of explicit violence and gore. Second, there’s an abundance of scatological humor, from constant would-be jokes about flatulence and body parts to an extended bit of business involving a toilet overflowing with excrement that he and cinematographer Bruce McCleery push into our faces repeatedly. These become the two refrains that punctuate the picture, but Ayer refines them as he proceeds, showing a particular fondness for torture scenes (Wharton’s wife and son were abducted and brutally murdered by Mexican drug lords, who were kind enough to film the procedure for his obsessive viewing), blood-splattered corpses (sometimes in CSI examining rooms) and close-range shootings, most of them directly to the head. A scene toward the close in which a body has been put in deep freeze is particularly vile.

The team’s elaborate theft comes to naught, anyway, because when they go to retrieve the loot from the sewer where they’d stashed it (an ironically appropriate venue), it’s gone. The DEA suspects them of being dirty but can’t prove it (we get lots of dumb interrogation scenes), and must put them back on the street. And the cartel doesn’t much care whether they have the dough or not—the fact that they stole it is quite enough—and sends out a squad of hit men to knock them all off, one by one. We get to witness three of the assassinations in grisly detail, lucky us.

By now a cute but determined Atlanta police detective, Caroline Brentwood (Olivia Williams), and her partner Jackson (Harold Perrineau) are on the case, and almost before you know it, she and Wharton are—quite implausibly—getting romantically involved. What follows is an increasingly twisty, but persistently brutal and overwrought, plot that casts suspicion not only on the cartel hit squad but on members of the team itself. A car chase and an old West-style shootout bring things to a conclusion smeared with blood and awash in dead bodies.

“Sabotage”—like Ayer’s previous film—is a grotesquely nasty piece of work that’s meant to provide exhilaratingly over-the-top action but ends up a rancid, nihilistic wallow in cynicism and gore. Schwarzenegger is apparently trying to act the part of a damaged man on a mission, but his performance basically consists of little more than generic sullenness and the ability to chomp on an apparently inexhaustible supply of cigars. Most of other actors in his team are wasted (especially Howard, who’s capable of good work), but Enos certainly takes scenery-chewing honors. Williams, on the other hand, brings a nicely starched dignity to her role, and Perrineau is genial and loose. Of course as mere cops they’re always several steps behind the curve, but the audience is meant to be, too. (We’re not.) On the technical side the picture isn’t much, either, though admittedly Ayer, McCleery and editor Dody Dorn wring some visceral tension out of sequences like one in which the crew invade an apartment building to capture—or preferably kill—the assassins who are out to get them. But it’s nothing we haven’t seen done better before.

Even the title is off. Who’s the saboteur and what does he sabotage? One presumes the authors just needed a catchy one-word moniker that would promise something dark and nefarious. If so, they’ve succeeded in a certain sense, because this movie is very dark indeed, and nefarious in claiming to be entertainment when it offers none.