Bad as this film is, the atmosphere at Casa De Manos is surprisingly full of dread; every second you're there, you get the feeling something's very wrong about the place. It has a similar oppressive feeling of wrongness to that of the house from The Texas Chain Saw Massacre (1974), only with a less immediate and visceral danger.
In a strange example of Narm Charm, the grainy film quality inadvertently lends a creepy credibility to the events depicted, as if it's a Super 8 home movie that just so happens to be about a vacation gone terribly awry. They even make a quip about it in the Mystery Science Theater 3000 episode.
