A good way to detect these environments is when you observe those who have been there longer not asking obvious questions. That usually means the trust issue is there. When you start asking those obvious questions, at first you get that feedback loop of slight condescension. But then others start asking questions and you often get a fruitful conversation.
Having worked outside of the startup world and in the startup world, I think this is a little more prevalent in the startup world because there is another axis besides experience involved in these conversations: how long the person has been with the startup. It's common to have an official or unofficial hierarchy based on experience but in the startup world, there is another hierarchy based on how long you have been at the startup. That additional axis means it comes up a little more in the startup world (in my experience so far).
Extends far further than the workplace. A few minutes in some of the more popular IRC channels on Freenode, you'll get the same experience. It's extremely frustrating, especially seeing it happen as an outsider to communities you like.
I feel like, in the same way that power generally corrupts people, "feeling smart" can corrupt the same way, coming down to the same attitude of feeling like you have an advantage over other people. Regardless of whether you actually are smart or not.
But if the snark is heavy without being warranted at all, it more than pisses me off. It reflects poorly on whatever you're representing and it's just bad communication. If all you have to offer is a lmgtfy.com Link, don't bother. Those immune to that train of thought won't, the others already have.