Snark at its best is not just pointless unfunny sarcasm aimed at an incredibly easy target.
It's not being rude for the sake of being rude, and should you offend someone "It's snark week" is not a defense. Nobody likes a Mean Girl, even on snark week.
For me, good snark is taking something that sucks, really sucks, and making it into something funny, something better. Sometimes, that's the only thing that makes it bearable.
Though anybody can whine, complain or make fun of someone, real snark to me isn't something you can just start doing on command, it's usually brought on by a thinly veiled sense of outrage. That's why I think the early UU Christian blogs did it better, because in some real sense they felt oppressed.