You're always making an impression on people, no matter where you are. But in a job interview, your behavior should be at its best. In case you're thinking this is something everyone knows and doesn't need to hear again, let me tell you a story.
I expected him to say that something had come up and he had to reschedule the interview. Instead, he said, "I'm just about to leave, so I'll be a little late."
He didn't offer any reason or make an apology, but that's OK. I said I looked forward to seeing him and I went back to work. About 15 minutes later, I got another phone call from him. He said he was standing outside the buildings, but didn't see a sign for our company. The fact that he said buildings (plural) gave me a hint and although he went on and on, I informed him he was at the wrong address.
He told me he wasn't at the wrong address because his GPS had brought him to the three white buildings. Apparently, his GPS knew better where I was than I did! I told him how to back track to my location in a lone, brown brick building down the street. He seemed skeptical, but about five minutes later, he arrived.
I went to the front desk to greet him, but he wasn't there. I looked around to find him in the hall talking on his cell phone. He waves me down and puts up one finger indicating that I should wait for him. I flipped through a magazine twice while I waited.
Once in my office, he put his phone on the table between us where, for the rest of our time together, it rang six times. Apparently he thought just putting the phone on vibrate was enough, but he answered two of the phone calls during the interview.
If he can't treat an interview with me seriously, I have to ask myself, "How would he act in front of a client?"
Remember that everyone you meet, whether a receptionist or a third-party recruiter, is interviewing you. If you're looking for a job, you need to act as though anyone could be asked by your next boss, "What was your impression of the candidate?"