They just want A job not, THIS job - Particularly in the current economic climate, candidates just want a position, any position. If you can't answer why you want to work for this company in this particular role, and are the best person to do that, save yourself the bother of applying. Contrary to what you may think, it's not a numbers game. You don't marry just anyone with a pulse, so don't apply to just any company with a payroll. As an employer, I want to know why you are the only person who can do the job.
They don't know what we do - You have to do your research into the company, its positioning, competitors, challenges, financials, recent news. For instance, in my sector, you have to know the difference between PR and advertising. I'm sure there are similar fundamentals in other areas which scream lack of research. It's hard to take a candidate seriously who hasn't put in a few hours getting the fundamentals down.
They mess up the basics - Turn up on time, wear a clean suit, bring an up-to-date resume which is free of typos, don't smell (e.g. of smoke or attack perfume), brush your hair, have clean shoes, don't wear too much make-up (especially guys!) or show too much cleavage (guys!!), don't sweat profusely, or in any way give a first impression which is not the one you intend. Your apparel and punctuality should not be noticeable. You should be what we notice.
They're dull - Companies want to hire fascinating, engaged and exciting people. The ones who ooze potential. So don't bore your interviewer with trivial accomplishments, bland perspectives, wrote answers or lengthy diatribes. Be different. I often ask myself - would I want to get trapped in an elevator with this person? If I can't imagine inviting them home for dinner or going to a bar with them, they're probably not the right fit. Keep your answers short, laugh your way through the interview, be yourself. This is supposed to be you at your sparkling best.
They exaggerate - During an interview the BS radar is on full alert and pointed directly at you. So just be honest. By all means, highlight your accomplishments but don't claim abilities which you don't possess. Honesty and humility are far more important than supposed superpowers. And don't forget, if you get the job, and your track record is a fabrication, we'll find out. Start the relationship on a solid foundation - in many ways it's better to underplay your role and then over deliver when you get the job.
In related topics here are the ten questions which interviewees never ask and a few pointers on how to get a job in PR. Companies are always looking to hire great people, so good luck!