Cripes, a cat hater! :) That isn't a blank expression; it's the expression of one who is hatching evil plots, ha ha. You know, like a boss you've had, perhaps, whom you disliked and whom you thought disliked you. Same expression. Really, though, I think it's just because the pupils of their eyes are so large. Gathering light and all that, so they can see you in the dark to pounce on you.

I always thought dogs have goofy, "please love me" expressions I scorn. Cats make you earn their love, though you never quite get it entirely. They are very self-centered on the whole.