You are right. But keep in mind, those pathological customers are everywhere. Reviews are a big factor when deciding between competitive products, and your competitors will face the same pathological customers.
ReadItLater's free version is rated 1 star less than the pro version. All of the 1 star reviewers appear to be worth ignoring.
That's possible, but they will be a factor in your business if they are unfairly slamming you in reviews.