The kind of people that will ride up behind you on a motorcycle and stab you in the back with a sword if you're too busy watching a quiet one to notice one of them coming.
So you watch your quiet rogue minding his business over there, meanwhile I'll be watching these noisy ones on motorcycles with their swords and knives out. This guy Sato is dragging his sword on the ground sending sparks everywhere, and as interesting as the quiet one might be, it looks like Sato is going to decapitate somebody in about 2 seconds. When was the last time you saw a guy get decapitated? You see quiet ones minding their business all the time, what is there to watch?
You watch the quiet one reading the book/magazine, and I'll watch the noisy one with the gun that says he's going to shoot down anybody that isn't scared of him/her. Whether people think he's/she's a bitch or not, the loudest one will kill you dead to prove he's/she's not the bitch, and the scared one will be the one to shoot (or cut somebody up).
You watch the quiet one reading the newspaper, I'll watch the noisy one with the gun saying he's/she's going to shoot the one that isn't scared of him/her (though people don't often warn you with words). The scared one is the one that will shoot.