Some people think that using the subjective case of a pronoun (that’s I, you, he, she, we, and they) is more refined and sophisticated than the objective case (me, you, him, her, us, and them). But when the pronoun is the object of a preposition (like of), using the subjective case just makes you sound ignorant and pretentious. That’s the case in this sentence from Yahoo! omg!:
You’d think a professional writer would know better. You’d think that an editor would correct such a mistake. And you would be wrong.