"I agree that they hunt by smell I also think that they use sight hearing touch and taste.
See my idea of a zombie is that a bacteria is infected in the body and slowly decays them while they are still living and the only part it leaves is the neveous system making the decaying process very painful driving the victim crazy, eventually the bacterium will enter the human population and since humans are herd animals we would move in huge numbers. The only thing that slows the bacterium down is meat because the bacteria will attack the alien in the body as a new source of food to decay. That makes it so the zombies are actually alive so you CAN kill them and it solves the why do they eat flesh and the newer the zombie the smarter they are meaning they could stratagy's and use weapons and machinery. The zombies will attack anything that they think is food aka anything that looks tastes sounds and smells like food such as meat. Now to me, I think makes much more sense ohh and I have this idea copyrighted."

"Zombies don't feel pain. They're just walking bodies that can use their functions for finding prey.

I don't think their nerves will be working very well; even with fatal injuries they are still about to function and hunt without running around screaming in pain."