how can we????

One meeting certainly is not enough but one thing to be war of is impressions namely becuase first impressions last a lifetime. If your first discussion gets off on the wrong foot you may be in for some stormy waters continuing the communication with each other. Another major thing to consider is that perception is 90% of reality so try not to give have the other perceive you as anything but who you are. If you can keep these in mind and realize no one is perfect so there will always be stumbling blocks so just recognize them, acknowledge them, apologize if necessary, and move on.

You can't judge anyone from one meeting. Like you said the first time you meet someone they will usually show their good side or even a fake side. After maybe four or five meetins you will start to see the real person. They feel more comfortable with you at this point and start show their other side.

Cos humans are all superficial by default, and they love to jump into conclusions.

Though, truley speaking its not wise to judge a person from the first meeting, as human beings we tend to fall into conclusions.I too agree with you.It takes time to understand a persons true character,and a person maynot reveal his true colors when you meet him for the first time.But,most of us are victims of the so called 'FIRST IMPRESSION'. You say that we need to meet a person 4 or 5 times to corresctly judge him.Quite true.But can you truthfully say that you have never judged anyone in the first meeting? Think about it.