Fake reviews
Reviews and ratings written or paid for by the seller, or against a rival, and presented as the independent experience of customers, so that the audience's trust in peers is spent on the seller's behalf.
People trust other buyers more than they trust sellers, and rating systems turn that trust into a number. Fake reviews counterfeit the number: employees and contractors post as customers, incentives buy five stars, review-selling services supply hundreds, and rivals receive ones. The buyer sees four and a half stars from two thousand people and reasonably concludes that two thousand people were satisfied.
The device is testimonial and bandwagon in the retail economy, and its scale has been measured: studies found that a meaningful share of reviews on major platforms were suspicious, that independent hotels and restaurants were more likely to have fake positive reviews, and that fakes clustered where competition was fiercest. Regulators in the United States and the United Kingdom now bring cases. Exploits Social Proof and Authority Bias transferred to peers.
Historical examples
Mayzlin, Dover, and Chevalier compared hotel reviews across platforms with and without purchase verification and found the pattern review fraud predicts: independent hotels with more to gain had more suspiciously positive reviews on the unverified site, and hotels next to a competitor received more suspiciously negative ones. Luca and Zervas used Yelp's own filter to show that fraud rose where reputation mattered most.
Mayzlin, Dina, Yaniv Dover, and Judith Chevalier. "Promotional Reviews: An Empirical Investigation of Online Review Manipulation." American Economic Review 104, no. 8 (2014): 2421–2455; Luca, Michael, and Georgios Zervas. "Fake It Till You Make It: Reputation, Competition, and Yelp Review Fraud." Management Science 62, no. 12 (2016): 3412–3427.
In advertising and commerce
The Federal Trade Commission brought its first case against a seller for buying fake reviews in February 2019, against a supplement company that had paid a third-party site to post reviews on Amazon. The United Kingdom's Competition and Markets Authority opened its investigation into review platforms the same year and secured commitments from major sites in 2020.
Federal Trade Commission. "FTC Brings First Case Challenging Fake Paid Reviews on an Independent Retail Website." Press release, 26 February 2019; Competition and Markets Authority. "Fake and Misleading Online Reviews." Case update, 2020.
Investigations by consumer organizations and journalists have documented open markets for reviews: groups in which sellers offer refunds for five-star reviews, services that deliver hundreds of reviews for a fee, and "review brokers" who coordinate them across platforms. Which?'s 2019 and 2020 investigations found such groups operating with tens of thousands of members.
Which?. "Fake Reviews: The Groups Selling Five-Star Ratings." Which? Investigations, 2019–2020; He, Sherry, Brett Hollenbeck, and Davide Proserpio. "The Market for Fake Reviews." Marketing Science 41, no. 5 (2022): 896–921.
Pick a product with hundreds of reviews. Sort by date. Are there days with many more five-star reviews than others? What do those reviews have in common?
In the wild
Short examples of the technique at work, each with what to notice. The same examples are questions in the quiz, where the answer is not given away.
The new blender received 340 five-star reviews in its first three days, most from reviewers with no other reviews and several with the same opening sentence.
What to notice. Counterfeit peer endorsement at scale; the timing and the shared phrasing expose it.
"Leave a five-star review and message us for a full refund," reads the card in the box.
What to notice. Incentivised reviews: the seller buys the rating the buyer will trust.
The café across the street received twelve one-star reviews in a week, all from accounts created that week, none mentioning a dish.
What to notice. Fake negative reviews against a rival; the same device in reverse.
Sources
- Luca, Michael, and Georgios Zervas. "Fake It Till You Make It: Reputation, Competition, and Yelp Review Fraud." Management Science 62, no. 12 (2016): 3412–3427. doi:10.1287/mnsc.2015.2304
- Mayzlin, Dina, Yaniv Dover, and Judith Chevalier. "Promotional Reviews." American Economic Review 104, no. 8 (2014): 2421–2455. doi:10.1257/aer.104.8.2421
- He, Sherry, Brett Hollenbeck, and Davide Proserpio. "The Market for Fake Reviews." Marketing Science 41, no. 5 (2022): 896–921. doi:10.1287/mksc.2022.1353