Answer:
I usually wear a yellow coat. I usually have a dark head. I make marks wherever I go.
You can see nothing else, When you look in my face, I will look you in the eye, And I will never lie.
My teeth are sharp, my back is straight, to cut things up it is my fate.
All about the house, with his lady he dances, yet he always works, and never romances.
You heart it speak, for it has a hard tongue. But it cannot breathe, for it has not a lung.
People take me on walks and I run and have fun. What am I?