My philosophy about books that I abandon, is that I can make no judgment about the book if I abandoned it. My policy on Goodreads was to delete the book from my shelves and I'm going to continue the same policy here. There are numerous reasons why I abandon books. The most frequent reason is that it's a library book, it's due soon and I've already renewed it once which is the maximum number of renewals. There is no way that I'm going to finish the book at this time. So I return it unfinished. If it's really important that I read that particular book, I may check it out of the library when I have more time. I may also forget that I was ever interested in it.
Yet sometimes I abandon a book because it made my blood boil. In some cases, this could be a sign that the author is doing his or her job. He or she is a gadfly. I like gadflies unless they metaphorically gore my ox. That's the thing with satire. Everyone finds satire great fun when it pokes fun at all the things that you love to hate, but if it pokes fun at things that you value a great deal, then it's not amusing at all. At this point people may start saying that I have no sense of humor. I'm willing to bet that none of you laugh if someone gores your ox. On the other hand, some people may have no ox, and therefore enjoy all satire equally.
Other times, there is a really important conceptual reason that I abandoned the book. I still feel that I shouldn't review it. It could be that the author later justifies him or herself, and I could come to see it the author's way if I continued reading. I just don't have patience with some perspectives which probably says more about me than the book. As a library student, I know that I need to value diversity and project neutrality professionally. I would never make any judgements about what other people choose to read. Of course, I make judgements about what I choose to read, and I feel that these judgments are more justified if I have read the entire book.