Late to the party - It is almost impossible to recover when you start off being late. Let's face it, you've probably never met the person you will be interviewing with and showing up late just sends so many bad signals. Poor planning and lack of time management immediately come to mind. Sure, there are reasons for being late: an auto accident, being held at gun point or some other life-threatening scenario - all other excuses are non-starters. Overall, it's just not a great way to make a good first impression.
Driving while interviewing - Why bother? Dropped cell calls, bad reception - not to mention your loss of focus - just to name a few. If the message you want to convey is that you don't put much effort into important meetings or phone calls, just try driving and interviewing. Soon enough, you'll be driving and crying. If you can't invest 60 minutes from a land line or even via cell phone but in a stationary location, you probably have a bigger problem than just time-management. I simply don't get this one. No driving while interviewing, please.
Ask about vacation time - That's not even smart! Let's put this one in perspective: you've never met the hiring manager, have no clue about the culture or the team and they don't know anything about you. So, yeah... asking about vacation or PTO should work. Are you kidding me?! The message re: your work ethic will be heard loud and clear. Even if you're a workaholic, it won't matter. Leave those questions for later - like after the initial interview!
Disparage your current employer - It seems like it'd be simple enough to grasp, and may do, but there are some who feel obligated to engage in a dialogue that throws their current employer or bosses under the bus in an effort to connect with the interviewer. This sort of behavior sends a clear message of who exactly you'd be working with long-term. Even if you have a toxic boss or hate your current employer, it's not good form to share that much information on your interview. Leave that at home.
Never have any follow-up questions - Usually at the end of an interview, the person you are meeting with will ask if you have any questions. "No" is always the wrong answer. I usually request candidates to prepare 5-6 well-thought-out, open-ended questions to ask at the end of the interview. Do your homework, and make sure they know you have prepared. Asking intelligent, well-thought-out questions goes a long way to let them know you value their time.
