Keep in mind that career fairs are attended by people looking for a very specific kind of hire and/or they're just looking to get you to visit their careers website. A Google engineering recruiter at a Stanford career fair isn't there to chat an English major who is excited about the computer science for liberal arts majors course they took. They're basically not interested in talking to anyone, as because standing there all day saying "tell me about yourself" and answer "what does you company do?" is mind numbingly boring once you've done it a few times. If you're working at a career fair, the only thing you're looking forward to is an after hours happy hour.