IMHO, if you read the whole thing and it is not "defective", you bought it. Otherwise it is a bit like eating the whole apple and wanting a refund because it wasn't as sweet as you expected.
As a reader, I agree. You take a gamble when you buy a book or a movie ticket. It's up to you to read the sample, the reviews, etc. and do the due diligence. When I still end up hating something, I figure, whatever, at least I helped support the publishing industry today. And since it's an e-book, it won't be cluttering up my house.
But in the case of the book where only the sample was properly edited, I can understand feeling like you were the victim of false advertising, and possibly demanding a refund. If you hated Drive because it wasn't the action-packed flick the commercials led you to expect, well, maybe you should have read some reviews rather than demanding a refund afterwards or suing the studio for defrauding you. But with a self-pub book, you may not have anyone to warn you away, until other reviews start trickling in.