I try not to go by first impressions, but honestly it's hard not to. If a new person behaves like they are a smart a$$, know-it-all, etc. I generally try not to associate with them but sometimes the person can be very nice at first and their rudeness escalates..

I remember a girl, I'll call her K and she was such a sweet person at first. She was always nice to everyone co-workers, supervisors, guests you name it she was always polite. The first time she was rude to one of the Cash Control people I didn't think much of it, just that she was having an off day. One day not long after that I was in the back counting stock and she comes in and tells me to start blowing-up basketballs, I asked her who told her to tell me that and she didn't answer me. I kept counting stock because it's not like a supervisor had told me to do it. After that she became SO incredibly bossy that I avoided her at all costs, not only to me to everyone including my supervisor and sometimes guests. Last I heard, she got into a fight with another employee and was fired for it. She lasted the whole of 3 months.

Long story short, I learned that maybe you should wait a while before making a final judgement on someone.