I think we all have had to wear a 'Mask' at one point or other in our lives.
There is a difference between a 'superficial' mask (one that is used to create a false impression, and / or to beguile) and maintaining a facade... which in strict observance to upholding respect toward others and maintaining a semblence of decorum in society - is inevitably needed.
I guess most of us would constantly maintain a facade. However, I think this instinctive weapon is not necessarily used to create a false impression... rather, it is used to protect ourselves.
To the undiscerning eye, laughter would signify happiness, and tears would show sadness. That arrogant strut means: Hey..I'm Cool. Words of empathy means that you can absolutely trust that person to understand. Sadly though, how much of this is real? More often than not, there's more to it than meets the eye.
Maybe all this has something to do with the human's ability to adapt itself to changes. To mould ourselves as per how the occassion deems it. We are all vulnerable in one way or another, and chances are, naivete at one point in our lives would have made us see how others can cruelly exploit a weakness.
I'm never quick to judge if a person is 'phony' or otherwise - unless he / she makes it soooo blatantly obvious that your hairs prickle and stand on end with every sentence said!
Some of us may be fortunate enough to have friends / family who accepts us the way we truly are... but with people whom we are quite unfamiliar with, or acquaintances, for that matter - I think all of us do try to project our positive aspects. Simply because i.) it saves a lot of explaining and questions ii.) It protects feelings.
Honestly - how many times have we felt the urge to say : "Oh just shut the F*** up, b****"... and what actually came out was : "Ok - you are entitled to your own opinion, but I would have to disagree"
No matter how we carry ourselves in public... so long as we stay true to our beliefs and respect others no matter what theirs are, I think all of us can give Jim Carrey a run for his money anyday!