Condescension and open conceit feels like the norm on GAF...
Or am I wrong altogether and people tend to be snobs about everything all the time?
I don't know that you're necessarily wrong, but it seems like that opener is an admission that you recognize there are a lot of users (not just GAF, but any form of social media) who tend to approach any possibility of disagreement with - if not outright hostility - a general defensiveness that assumes someone absolutely wants to fight you at all times.
Condescension is just one of the pre-emptive defensive moves people employ without really thinking about it, or why they're doing it. But if they can put on the front like "it's not really even worth your time to try fighting me on this because it's fairly obvious I'm like, a hundred times smarter than you on this subject" to dissuade that fight, they'll do it.
It's all a matter of the mindset with which you enter into any bullshit session: Are you looking to share opinions/ideas, even if you disagree with them? Or are you looking for someone to be wrong about something so you can cave their shins in?
I like learning shit I didn't know before I opened my fat mouth, personally. I can do without people being rampant assmouths about it, (and I could do better about the shit dripping from my own tongue, really) but if I find a "film snob" on this forum, I tend to pay attention, because it's possible I'm about to learn some shit I didn't know before.
It's happened more often than it hasn't.
What I find more annoying is people who demand those who dislike something to thoroughly explain themselves
Yeah, that one's weird.
"Why do people like this movie I didn't like as much as a bunch of people who obviously love the living fuck out of it?"
It's like general consensus doesn't exist for some people, isn't a researchable, understandable thing, unless it comes out of a thread they started. There isn't an easily findable, thoroughly explained set of answers just waiting to be read, until they themselves think to ask the question.
Of course, usually they don't really give the smallest fuck about any of those answers, because the real purpose of asking that question is to make sure people understand how sharp the edges on their precious, individual snowflake really are.