Common sense is the collection of prejudices acquired by age eighteen.
Albert Einstein
Things that stir the soul of one culture need not make any sense to any other culture.
Other than having a professional demeanor while at work, I see no reason that a person would need to be a social chameleon. Sure you may dress up when you go to a costume party, or quiet down when attending church, but in general, one should be able to be oneself at all times.
My friends, family, and coworkers could all easily distinguish activities I probably have engaged in from ones I probably would not engage in if given a list, and those will generally all match up very well(not counting the lists from a current or former girlfriend, but those things are private between the participants and need not be shared)
Then again, I suppose not everyone has the foresight to select and train for a career they actually enjoy, and so must put on a mask every day lest their coworkers see the quiet desperation in their eyes as they try to 'make do'
And I suppose that many are not confident in and of themselves so that they feel they must wear a mask to get people to like them, a mask that they must then wear any time they are around their 'friends' who are not really their friends, but friends of the mask that they wear.
Just considering those two situations is depressing enough, I don't even want to consider a person that feels a need to wear a mask around their own family.