Indefensible on a moral level, Rob Zombie’s perversely watchable follow-up to his much-reviled cult hit House of 1000 Corpses is loaded with filmmaking energy. Don’t get me wrong. The Academy won’t be rushing to reward the heavy-metalist for the scenes of psycho clown Captain Spaulding (Sid Haig) and his satanic, serial-killing family — son Otis Firefly (Bill Moseley) and daughter Baby (Sheri Moon Zombie, the auteur’s wife) — on their torture/killing spree through the backroads of Alabama. The moment when Otis gun-rapes a scared, naked woman (Priscilla Barnes) in front of her husband (Geoffrey Lewis) is not slated for Oscar immortality. But every frame of this scuzfest oozes with the freaky-deaky love Zombie feels for Tobe Hooper’s 1974 Texas Chain Saw Massacre and all those slasher-horror flicks he must have watched at drive-ins through grimy windshields. Tiny (Matthew McGrorey), the brother the Fireflys keep hidden, is a direct homage to Leatherface. This rough, grainy freak show looks like something you want to scrape off the screen. I mean that as a compliment. You’ll get creeped out big time as Sheriff Wydell (a terrific William Forsythe) exacts his own vengeance on the family, ting with Mama Firefly (Leslie Easterbrook), the hooker-matriarch he has locked up in his jail. There’s humor, too, when the sheriff hires a film critic to decode Captain Spaulding’s fixation with the Marx Brothers. Let’s hear it for the Southern-fried soundtrack, from Buck Owens’ “Satan’s Got to Get Along Without Me” to Lynyrd Skynyrd’s “Free Bird,” playing over the blood-soaked finale, which manages to wed The Wild Bunch to Thelma and Louise. In Zombie’s hands, the Fireflys emerge as the twisted underside of the American family, with every dark impulse made flesh.