First Impressions... Do They Really Last?

Just another random question that found its way out of the crazy pile of question my brain has. So as the title says/states, do first impressions really last?
There goes the saying that first impressions lasts. This might be the reason why girls take time to fix themselves up. They might bump in to some cute guys and they want to leave an impression of being poised, beautiful, sexy, cute, and many other more positive, confidence boosting comments. Guys, on the other hand, also fix themselves up nowadays, and probably for the same reason girls fix themselves up.
From my point of view, I don't think first impressions last. Yes, they do matter but they don't really last. It's like giving a person a very old cassette tape with a lot of great songs inside. The person will have second thoughts about accepting this "antique" gift because it's not presentable enough. The first impression strikes again.
I had experiences of the deceiving first impressions and through time they had changed. I studied in an all girls school. Almost everybody are girls - the teachers, students, sisters, staff and even guards!. (exemptions would include some other staff and some guards.) The first time I had a male teacher was during my first year of high school. Oh yes... I had some weird feeling during his class. At first, I thought that he was boring, but no, I was wrong - very wrong. He was the total opposite of what I have thought he was in the first place. To cut things short, he was fun, and I had never thought that he was boring ever again.
Some of the feedbacks I had on the first impressions my friends had on me were quiet, snobbish, mean, etc. Ha! I'm not even an inch, no, a centimeter near what they were judging me to be. Of course, these impression all changed. We became great friends, and we still are.

Do first impressions last? I don't know for you. All I know is that in my case, they don't.