Do you find that intelligent people usually lack in social graces?

I observe people a lot, both on and offline in my everyday endeavors. And I also notice patterns and likenesses. I have come to notice that often, people who are seemingly intelligent are usually brash, crude, cynical and sarcastic as if this is the only way to be or as if it is the latest fashion of personality to wear. Or is it the other way around perhaps? Because all too often I'll ask a question, or read/hear someone elses and usually that question will be met with said sarcasm followed by immature humor? So maybe, sarcasm and cynisism are a way to appear intelligent when you really aren't, you know, like designer knock offs?