In one of my sidelines, I'm a freelance musician. Over the years I've learned how to keep a smile on my face, under pretty much any circumstances. This has proven to be a valuable skill in my day job as well.
The smile is more subtle in the workplace -- just a cheerful disposition -- but it's still there. And it helps that I am in fact a generally cheerful person.
As for knowing how to show an appropriate level of passion, I would expect this of a senior level person as well, because they will be interacting with colleagues, customers, etc.
An artist friend of mine was mass-defriended on facebook after a vitrirolic angerpost about religion. Everybody there knew his opinion on religion I know for a fact many agreed with him, but they didn't want anger and unpleasantness thrown in their faces. This has undoubtedly affected his ability to get work in the future.
The smile is more subtle in the workplace -- just a cheerful disposition -- but it's still there. And it helps that I am in fact a generally cheerful person.
As for knowing how to show an appropriate level of passion, I would expect this of a senior level person as well, because they will be interacting with colleagues, customers, etc.