With only the most obvious references to horror classics and a childish approach to growing up, Max and Sam Eggers' genre exercise doesn't deserve Kathryn Hunter's smart, cunning performance.

If we live long enough, we won’t be spared from seeing the ravages of old age creep into our bodies, mercilessly corroding the things — like healthy hair and intact teeth — we once took for granted. A mean-spirited, abrasive hagsploitation exercise co-written by first-time directors Max and Sam Eggers (brothers of modern-day horror master Robert Eggers, with whom Max wrote “The Lighthouse”), “The Front Room” will only be bearable if you find those aging-related hardships — incontinence being one of them — creepy and funny. Otherwise, with the exception of a fiercely committed performance from “The Tragedy of Macbeth” Oscar nominee Kathryn Hunter, much of this well-crafted but dull film is shruggable.

Hunchbacked, twisted and with a tough accent, Hunter slyly plays Solange, the nasty surprise who doesn’t worm her way into anyone’s body (despite the constant and annoying teasing, “The Front Room” is no supernatural horror with a possession theme) but into the modest home of her stepson Norman (Andrew Burnap) and his heavily pregnant wife Belinda (a convincing Brandy Norwood). With a “Daughters of the Confederacy” certificate and frequent insults hurled casually at Belinda, Solange is an obvious racist. But what most unnerves the young couple about this extraordinarily Jesus-oriented old woman isn’t necessarily her abhorrent views, but her inability to control her bladder and bowels.

Perhaps they have a point, as Solange’s urine and feces regularly appear on various corners of their home, and the filmmaking duo aren’t afraid to show it. The stains are everywhere, even on poor Belinda’s hands, phone, and clothes. (In one scene, she stubbornly doesn’t change her dirty shirt for a ridiculously long period of time, a calculated decision that needlessly hammers home the film’s vile intentions.)