In my professional life in the real world, I've heard the word "snitch" used as one of the most damning insults of a person's character more often than I can count. I get the mindset behind the "snitches get stitches" mantra that has permeated the culture of drug use - it's the same as playing in the playground as kids, when mom doesn't see it it doesn't happen unless someone tells her - but it always amazes me at how much this ideal is accepted. You walk into a room with a bunch of potheads - and comparing potheads to meth users is like comparing toddlers on a tumbling mat to Olympic gymnasts - and they're going to tell you that snitches get stitches in the same tone they would use to tell you the sky is blue. It's become a fact in drug circles, and it's an almost unwritten part of The Salton Sea's tense plot. No one ever says "Hey, this guy's a snitch, he's in danger" - but it's understood from the first time we learn about Danny Parker's role.
(By the way, that's an awful trailer. The movie doesn't have the plot or tone it implies. Think noir!)