There is this saying, "First Impression is Last Impression", but is it really TRUE..?? Because at first everybody will try to act nice and leave a good impression. And if a person decides about his/her behavior, then that is the biggest mistake. You might say, "First impression is not the last impression but long-lasting impression". Why ?? Because there is always a chance to rectify the "first impression".
Consider an example, there is a new professor in your college with very very dull expressions, you will definitely make a comment that he/she is not good OR may be laugh @ him/her. But have you ever thought why he/she is like that. Another example, if a person is always smiling and like to make friends or will talk like a cartoon for that matter. Does this mean that person is not serious or he do not understand how to behave ? A big "NO" to this thing. These are the ways/perspectives to live your life. Some people are always smiling, some are serious. But if you want to judge a person with its Wrapper then Be Careful. It is true that "Product is only purchased if the PACKET is good", but sometimes it may happen that, product is good but packing was not done properly.
So, just give a second chance to the person for whom you have given your opinion. You may be wrong @ first time. There is always a reason behind the behavior of a person. Also, never take anybody for Granted or never Underestimate anyone for that matter. Because, "Nobody is Perfect and you are nobody". Whatever you think for somebody, may some other person is thinking the same for you.
Always try to understand Heart. If you can't understand then you do not have any right to judge that person........if you understand then you will not judge that person.