Is it okay to look at another person's negative characteristics to improve my own?

Last weekend, I had the opportunity to meet a person at a two-night convention. We had dinner both nights. The first night was okay, given I was a bit tipsy and he was definitely a gentleman to not allow me drive home. We had a great conversation, but, thanks to the alcohol, I wasn't there fully to really assess his personality. However the last night we had dinner, I figured out his true colors. I became turned off to his outlook on life. We share the same zodiac sign and I think that's why I am turned off to his characteristics. I've done a lot of research with the characteristics of my sign and read that from him. I am afraid I'll go down the same path and realized that I want to make changes to myself.

So, is this a normal human reaction to want to improve self? Am I being selfish reacting to someone's problems to improve my own? Please share your thoughts. Thank you.