Even the mariachi bands are depressing in a Todd Solondz movie. From 1996’s “Welcome to the Dollhouse” to the new “Wiener-Dog,” Solondz has been one of the most reliable miserablists in movies. He treats the losers and posers of the world with equal contempt. If there’s anybody in his movies he seems to have an affinity for, it’s the few amoral predators who prey on the rest of us. They’ve at least figured out the rules in such an unfeeling world.

I’ve gone back and forth on Solondz’s movies – I really liked his little-seen last film “Dark Horse,” but have found other films to be mean just for the sake of meanness – and a pretty repetitive meanness at that. It plays Saturday night at the UW-Cinematheque, 4070 Vilas Hall, for free on a double bill with the documentary “Weiner.”

“Wiener-Dog” features at least one blameless character – a dachshund that moves from owner to owner over the course of the film. The opening shot features a shot from the pooch’s perspective, looking up through a wire cage to the blue sky above, and the rest of the film he’s an adorable little observer of humanity in its darkest hour. The dog almost looks like he could be a Solondz character, waddling along on ridiculous little legs with a strangely dignified expression on his face.

Like Solondz’s “Storytelling,” “Wiener-Dog” is an anthology film of sorts, each segment functioning like a short story in a linked collection. The dog’s first owner is a boy in remission from cancer, and his clueless upwardly-mobile parents (Tracy Letts and Julie Delpy). This is a familiar dynamic for Solondz, as a wide-eyed child asks questions about the world, and his parents give answers that are hilariously awful. Delpy’s mother cheerfully spins all kinds of lies about how dogs don’t mind getting spayed, and how terrible the consequences if they aren’t. Somehow her explanation takes a detour into Islamophobia.

The second segment revisits Dawn Wiener, the protagonist of “Dollhouse,” now played as an adult by Greta Gerwig as a mousy veterinarian’s assistant who rescues the dog from getting euthanized. The third segment features Danny DeVito as a sad-sack screenwriter turned film school prof, ignored by his students and disapproved of by the faculty, who comes up with a novel form of revenge against the school. In the last segment, Ellen Burstyn plays a bitter elderly woman who gets a visit from her ne’er-do-well granddaughter (Zosia Mamet).

If you’ve seen a Solondz movie before, none of these scenarios will seem particularly new. People in his movie shuffle through their days, hurting each other almost involuntarily, not even aware of the wounds they’re inflicting. The performances are all flat and affected, which suits some actors better than others; the normally effervescent Gerwig just seems like she’s been tranquilized, but DeVito is terrific at finding the comedy and pathos in Solondz’s words.

There are moments of reverie in “Wiener-Dog,” such as a sublime sequence where the old woman is visited by a crowd of red-haired girls, each of them representing a different, better path she could have taken in her life, but didn’t. And then there’s a beautiful scene where the young boy and the dog play in the house while the parents are gone, the air filled with down feathers as they jump on the couch, “Clare de Lune” on the soundtrack.

But you can’t trust images that pretty in a Solondz movie – he uses the same music a few minutes later for a slow pan of an endless trail of dog diarrhea in the driveway. Beauty, ugliness, love, hate – it all looks the same from Solondz’s detached perspective.