Go home, nothing's so mystical about Slint. Or if there's any, they won't ever reveal. I feel the boredom and trivialities comes up as the result of a firm boundary built between the band and the documentary as if all the members wanted to say was "Yeah, whatever."
Boiling down a legendary band's mystique into being a bunch of blasé high school kids who can't be bothered and make tapes of themselves farting in different positions. Amazingly preserves a deep melancholy and stands as a good lament to the passage of time.