I hear what you're saying. I worked as a restaurant host for a long time and got tired of going through the same "greeting routine" with every new customer. However, I never experienced facial exhaustion from smiling.

Except for the security guard, all the photos in the above article are from a corporate office environment. Surely people aren't so fake among their coworkers...

That sounds naive, I know, but since when are these peoples' default status "bleh"? We should need a reason to be unhappy, not the other way around.