Every company has a corporate culture: this is not a concept limited only to hip start-ups that use medicine balls as chairs and install rock walls in the break room. There is an attitude to every company, from the smallest two-man operation to a multi-national corporation. If your company has the profile of Disney and you're more of a Hamlet, it doesn't matter how well-suited you are to the work, eventually the environment is going to grate on you. We aren't saying that you need to quit as soon as you realize that people in the office are different from you, but you have to ask yourself if this is a company that is going to offer the kind of growth and development you need. If you don't like the way a company feels, how can you aspire to run it one day? Look at the little things. Is this a company that encourages feedback among co-workers? Does your boss value flashy displays over hard work? Are you working in the last stronghold of an old boys' club when you'd rather be in an office that isn't musty with the smell or whiskey, cigars, and chauvinism? The little cues can be a big deal, and at the end of the day, where you're working can be just as important as what you're doing.
2. You Don't Fit in With the Corporate Culture