Exactly. The same problem happens on amazon all the time. The only difference is that amazon shows who has a verified purchased the book, but still, it is very easy to review-bomb a book on amazon, and they do absolutely nothing about it. So, I don't really see this as an issue with goodreads per se. It's just a general problem with moderating user generated reviews, or at least it's a problem with large companies such as amazon moderating (or not) those reviews.