OMG I can't stand this. Look, it's fine if you have heard of a more obscure film or show and want to recommend it. But don't act like a snob because of it- it smacks of "Look at how much of a movie buff I am! You simpletons only like what's popular right now!"
8. Pretending to be into something way more obscure than what you actually like.
"Oh, well, all the regular people like Star Trek, but I'm only into Jason of Star Command. It's kind of an underground cult show, you probably haven't heard of it. The DVDs are out of print, too. It's more sophisticated than Star Trek, and it doesn't spoonfeed you explanations for everything. You probably wouldn't like it." (Or substitute Doctor Who and Sapphire and Steel, I guess.) Again, nobody ever feels the need to disavow their love of the popular books, shows and movies, unless there's some weird self-reproach going on. And hipstery obscurantism only validates the notion that popular stuff is automatically schlock — which makes it more likely to become schlock, because that's what everybody expects anyway.
Also agree with this. Criticize the work, not the fans. If you do the latter, forums just devolve into little cliques, and that's no fun.
3. Looking down on some other group of fans
Whenever people feel uneasy about their own fandoms, the natural thing is to displace that onto hating some other group of fans. You might suspect, deep in your heart, that your love of Thundercats is silly — but hey, at least you're not a Twi-hard. And so on. This is not cool. By all means, offer a reasoned, informed critique of Twilight — there's plenty to criticize — but don't look down on the fans. Because trying to create hierarchies of fandoms just results in some people feeling unwelcome, which makes everything smaller and less interesting. And you know, the fine distinctions you're making between the brilliant thing that you like and the terrible thing that other people like will be lost on many, many people. They'll just hear that everything is terrible, and this translates, in the minds of creators, to "We shouldn't ever try to make things not terrible, because nobody will notice anyway.")
"Chicken tastes like chicken!"- Space Ghost