Poker Face (noun): an impassive expression that hides one's true feelings. Having a poker face is both a gift and a curse. While you can hide your thoughts and feelings from everyone else, a lot of people will think you're arrogant and unemotional. In a lot of circumstances, it is helpful because you want to hide how you're feeling. But on the odd occasion where you are opening up to others, they find it hard to believe because your facial expressions do not correspond to how you claim you're feeling.

9. But others might think you're sad/low most of the time.

Just because you don't have a smile plastered on your face at all times, people think you're depressed.

10. People who don't know you too well find you intimidating and unapproachable.

First impression: Someone with an attitude problem.
"Screw you, world!"