Very few people bug me as much as the fake smart person! And you're spot on here. First, as my mother always said, if you're smart, people will know it, you don't have to tell them. And the word vomit! Ugg! Often, for me, that's the first clue; if a person is either using way too many words or using words that are completely inappropriate to the context and tenor of the conversation (ie, using unnecessarily large words in a casual chat at the dog park), I know they're trying too hard to "look clever." And then I'm out.