The Walking Dead is the only show in America that all of my friends watch despite the fact that we all mostly hate it. I've seen that phenomenon with reality TV shows (the audience of Jersey Shore is made exclusively of people who only watch on the off chance that one of the characters might choke to death in the middle of an episode -- but I'll let Dave talk about that), but never with a serious, scripted television show on a network known mostly for its quality.
This isn't the place for me to talk about why this show is bad (the pacing, unlikable characters, not enough zombies, a lack of fresh ideas, child actors, what's-her-name, Rick's terrible accent), and I know that taste is subjective. Just because all of my friends watch the show begrudgingly doesn't mean the restof the world does. That said, we have a Forum where people can talk about movies, TV shows, music, life and whatever else they're interested in. Everyone's usually pretty articulate and thoughtful, it's nice in there. Here are some quotes from various folks in the thread dedicated to The Walking Dead:
"Why are the writers doing their best to make us hate the main characters?"
"Man, this show is getting more and more soap opera-y every week. They really need to get back on the road because it's starting to stagnate."
"I was trying not to dislike Dale and Andrea, I've failed."
"I think at this point, the words that come to mind when I think of Lori are 'useless' and 'no redeeming qualities.' That's probably not good for your leading lady."
"Yes, I do hate the shit out of most everybody."
It's not like we have a special section of our forums for people to hate a TV show. Those are people in a thread reserved for fans of The Walking Dead! And the weird thing is that they are fans. The people who don't like the show don't watch it, but the people who love this show hate it. Go to the comments section over at the AV Club whenever they recap a new episode, and you'll find that most of those commenters are similarly pissed off at the show. The show that they keep watching. Every. Single. Week.
And why do they do that? One word: Hope. And now for some more words: Everyone who watches The Walking Dead isn't watching it because it's good; they're watching it because it can be good (and because Daryl rules). When I heard about this show, I was on board because I thought, "This could be either a show about people fighting zombies OR a show about interesting, diverse strangers trying to set up a new life at the end of the world, and also there are zombies in the background." It is, unfortunately, neither of those shows (it's a show where 12 unlikable people get into tense whisper-fights inches from each other's faces and between two and four zombies get killed every episode to remind people that HEY ZOMBIES). But I keep watching because, one day, it might be one of those better shows I envisioned when the show was first announced.
Some people watch because the graphic novel on which the show is based is awesome, and they're holding out hope that, one day, the show might be as good as the comics. Some people keep watching because it has all of the ingredients of a good show (money, the creative freedom a network like AMC allows, great source material, lots of characters, a liberal amount of side-boob, zombies), and even though it hasn't embraced those ingredients yet, it still might some day.
The Walking Dead is successful because people are tuning in but watching a different, better show in their imaginations, every single week. We, as a television-viewing audience, have never been this optimistic.