Why are ALL of the comments on Facebook movie trailers always positive?

This might not be the best sub for this question, but I couldn't think of anywhere else to post it. Every time I see a movie trailer on Facebook, all of the comments allegedly from "real" people are OVERWHELMINGLY positive. I'm talking about maybe one negative comment for every 20 positive comments. This seems to go completely against the grain for the normal online trend of negative responses being way more outspoken than positive. Has anyone else noticed this? Are these all bot accounts? I've seen it on every trailer I ever come across on Facebook.