Australian hotel chain fined $2.2 million for manipulating TripAdvisor reviews
https://edition.cnn.com/travel/article/australia-tripadvisor-hotel-fined-trnd/index.html
Though manipulation of customer reviews must be punished, extreme bad reviews by malignant customers must be excluded from reviewers.
So, there should be evaluation of reviewers to make sure that each reviews are trustworthy.
To make it clear, reviewers who have repeated negative posts should be marked by authorities, and if it continues, the reviewers should be lower ranked.
Though I don't think it's the complete system, malignant posts will be decreased to an extent by this system.
