n888
This is an interesting series on fake reviews: http://www.sitesell.com/blog/2017/07/fake-reviews.html
The company became interested in the topic because a competitor was training their affiliates to write fake reviews of the company's product as a bait-and-switch tactic. (They later did a study with methodology that showed their product does a 33X better job at enabling individuals to create high-traffic sites.)
Some of the worst niches, I’ve noticed, are those that have the potential to prey on people due to the nature of needs - health, make money online, pain relief, weight loss. If you can find a fair review when searching on product reviews, it’s pure luck.
I imagine that Google’s AI component of the algorithm should eventually be able to recognize and penalize reviews that actually do the customer a disservice. Until then, some of the suggestions in this thread are excellent.
Hope you find the link useful.