There have been a few threads about this previously. Asking viki to disable reviews until the show finishes. And also put a couple of lines below the Review category, saying “A review is for writing your opinion of the show after you watched it. Don’t base your ratings on hopes and liking the main cast, or on the video being available or not in your country”.
But… nothing! For now, let’s all go and put a thumb now and then flag the review for “inappropriate content” (although does not describe the problem well, it’s the closest one may choose). I make it a point of doing it regularly. Let’s all do it.