I guess I have a "look" that makes me appear "mean".
Now I know that I can give a look that will melt ice and freeze fire. If you cross me, you'll be on the receiving end of that... It's a classic and I learned it from my mother. :-)
But that's not what we're talking about.
The women in my family have piercing blue eyes. We are watchers. We take it all in. We aren't fake or phony. We just are. We tell it like it is.
Maybe that combined with the piercing blue eyes makes us look mean scary?