When do you know someone?

Question

This questions seems silly at first but it really is not. Divorce rate is very high in many developed countries and one would think that people know what they are getting themselves in to when they choose to commit their lives to one another. Or what about cases when a trusted friend breaks his word and gossips on you?
There are also people who claim to be friends but really are not since you never communicated much with them and do not have a lot in common.
These become more complicated when the relationship is unbalanced. Examples: would rich people or pretty gals know if people are out for their money or looks?
How do they circumvent that? If pretty gals only mixed with pretty gals, they would be labeled as "snobbish" when in actual fact they are simply taking wise precautions.

Answer 1

Never.

The best you can do is accept (or reject) them, based on how you perceive them. That may change when you know more.

Answer 2

you only know someone when you know yourself!