How does Bradbury make the Mechanical Hound seem evil, menacing and destructive?

In addition to the above, for me what makes the mechanical
hound seem so menacing and destructive is that, for the most part, it can't be
stopped. 

A real dog, no matter how large and ferocious, is
not as indestructible as the mechanical hound seems to be.  A dog can be fought against,
at least.  A rock or a big stick, whatever, can ward off a dog; not to mention a piece
of meat.  But the mechanical hound does not stop, will not back off, will not lose
interest if you show submission.  The mechanical hound leaves a human with no options. 
That's scary.

Except one, of course:  fire.  But unless you
happen to have a flamethrower with you, you're out of luck against a mechanical
hound--or at least that's how it seems. 

Finally, the
mechanical hound itself is not evil, since it's a machine.  The people who program it
are evil, but the hound itself is not.