There is kind of a tail effect to sarcasm, in my experience.
Stupid people don't get it, but, interestingly, some of the smartest people I know (think theoretical physicists, etc) don't get it either. You say something sarcastic, and they respond point-blank: "why did you say that, that is not true". The Sheldon meme not getting sarcasm in The Big Bang Theory is truer than one might think.