I don't think every anime fan is like this, but this is something they wouldn't like to admit. It's pretty easy for them to get snidey to someone who didn't find an anime enjoyable. Not to mention, whenever you are positive about something for logical reasons, they would come back to say "so if you like this, why didn't you like this other thing you said it was trash?".
I think this is how these people survive. Because in the anime community there's no bad reputation regardless of their actions.