I've picked up books in bookstores that I thought might be sketchy, quality-wise, and read enough to decide I couldn't get through it. I didn't buy them though. A book that I reacted to the way you did Twilight is The Da Vinci Code (didn't buy it, I borrowed it). I had to force myself to read the entire book, slogging through what I felt was much horribly written prose. Yet it obviously appealed to huge numbers of people.

What a marvelous perspective on your revision process! Sculpture is a nice metaphor for the stages of taking draft X to a polished book.

Another way to think of big revisions like this is as major surgery. I have to open up the manuscript, remove many parts and check them for problems, repair them then put it all back together so it's again a living, breathing thing. It can certainly be scary when it's all lying there on the operating table, but the rewards are great when you're finished.
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If you now get a raft load of dancing zombie books, you have only yourself to blame. ;-) Thanks for clarifying one of those mystifying agent comments I've seen in rejection letters. It makes perfect sense.