Here's the thing about zombies and the entire sci-fi/fantasy premise: It's complete bullshit. When people die, they swell up because of all the microbes and gases in their intestines, sometimes they burst, they smell real bad ... and that's it. Dead is dead. The very absolute end. Period. I've seen dead bodies a couple times in my life. I saw my grandma when I was 15. My aunt and uncle made the faux pas of having her casket left open. She looked well made up, hair neatly combed, slightly plastic and very dead.
Another time I was working in a retirement home for something like four dollars an hour and one of the long-term vegetative geriatrics in the retirement home died. The charge nurse didn't notice for several hours because, well, he never moved and was always asleep. His gurney was wheeled out of his room and into a hallway. His body was covered in a sheet. Aside from the fact his emaciated chest wasn't rising and falling, it wasn't much of a change from his prior state of being.
Dead people are without exception always one thing; very still. They don't get up and dance and they certainly don't rise up and start roaming shopping malls for human flesh.
If you are medically brain dead, you have no lower reptilian brain. You have no desire or compulsion to eat, let alone breathe. You can't see, hear, smell, taste or touch. Sorry Kirkman, zombies can't "smell" fresh human blood.
Prior to AMC's extravaganza, there was a plethora of zombie flicks. Like The Walking Dead, many take liberties with making zombies look as comically gory as possible. Zombies without limbs come out with their teeth gnashing. Zombies without spines slither menacingly toward the protagonist. Even more improbable, zombies without abdomens come lunging out of the dark, hungry for flesh. The trouble is, nothing without a digestive system, along with that all-important nervous system and circulation, has an appetite. Even invertebrates like parasitic worms aren't interested in lunch if you cut them in half in biology class.
I can't write fiction about zombies or any sort of zombie-sponsored apocalypse because some part of me is still a 12-year-old biology student who is gunning for an "A". I understand the basics of biology too well to suspend belief and stop snickering over the silly premise.
I would more likely believe in fucking unicorns living wild and free in Narnia or Middle Earth than zombies stumbling after their next "meal".
Now vampires, those I totally believe in.