We have all seen the disgraceful state of the Reviews feature. All the people who leave a bad review because it's not licensed in their region, or a good review because their favourite star is in it.
1. Disable the reviews submitting feature until a show has finished airing AT LEAST HALF of its programmed episodes.
2. Put a warning over the reviews, saying “Only use this for your opinion on the show, don’t rate it according to extraneous reasons such as subtitles percentage or having/not having a license in your region.”
3. On the flag, add one more reason to the flagging menu: rating for extraneous reasons (you may word it any way you like)
4. Have someone check the flagged reviews and delete them if they don’t conform to the guidelines.
Maybe people will still use reviews inappropriately, but I’m hoping that this will make them much less.
I know that people read reviews when the show has not finished airing, to decide whether to watch or not. But they can always read the comments, both on the main page and on the episode pages, to make up their mind. And that is why I didn't suggest to wait until the drama is completely finished but at least halfway.