He is heading somewhere wearing a white T-shirt dripping with blood.

At this point, it's believable to say he's grown used to the scent of blood. He has killed countless people, after all.

He stops his pace and stands before the door of the highest office—the Boss's room.

After a moment of hesitation, he knocks politely three times and waits.

"I'm going to get nagged about the blood again..."