This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / "Manos" The Hands of Fate
The "haunting" Torgo theme really is extremely sinister sounding...
For all this movie's faults, and there are a LOT of those, the atmosphere at Casa De Manos is full of dread, every second you're there you get the feeling something's very wrong about this 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.