If you know yourself at all, even a little, then you will know that no one you encounter is only as deep as what they present to you. We all put up the best façade of ourselves that we can.
That is not to say that it is inaccurate, or deceptive; it is the self we hope to be, think we should be, and how we want others to think of us. It is part of who we are, but in all honesty, it is a very small part.
To some extent, this is one way by which we try to make society better; by making our public self essentially a portrayal of what we aspire to be. But this is also why you should never take someone at face value. It is not hugely informative about their character that they display a virtuous self. This only tells you that they either want to be virtuous, or else that they know they are expected to be so, and thus they make a presentation of themselves that makes it easier to maneuver in society.
This applies to them and it applies to each of us.
There is nothing wrong with this. The problem only arises when you actually believe that the surface they show you is identical to the substance beneath it; and it is a problem when you believe this about yourself.