Last Saturday, I was desperate for Mozart sheet music for my 9-year-old’s music-class. It had to be for piano, and it had to be easy to play. Out of 84 options on Amazon, a book with 4.7 stars caught my. Later that afternoon, I needed to book a hotel for our summer vacation and I trusted the 1,310 reviewers on TripAdvisor who gave my pick an average of four stars, along with a good number of “fantastics” and “wonderfuls.”

Who are these reviewers? I don’t know. Yet I feel the need to scroll through everything written by people who have little in common with me.

Alex Haefner, who oversees content at Yelp, says the most prolific reviewers are “superpassionate about their local business experience and make it their hobby to write about them.”

Panagiotis Stamolampros, a lecturer on business analytics at the Centre for Decision Research at England’s University of Leeds, adds that they’re generally “extroverted and open individuals” who are active on social media.

Having many reviews for a product signals quality & also mutes any bad reviews

That’s certainly not me. I can’t fathom who would have the extra minutes in the day to write a thoughtful review.

June Cotte, a professor of marketing at Western University in Canada, says most sellers want to encourage many reviews as reviews as possible. “Having many reviews for a product signals quality, and also mutes any bad reviews.”

But the tactics to make this happen often render the star-rating scale useless. I’m not even talking about asking friends or relatives or paying firms to crank out five-star reviews. I’m referring to usually perfectly legit methods, like asking loyal customers to write reviews.

… popularity can become separated from how good something actually is

And popular influencers can sometimes make them meaningless anyway. “It can lead to stronger fads,” Princeton professor Matthew Salganik says. “At a certain point, popularity can become separated from how good something actually is.”

Finally, it’s hard to know what the stars even mean. Often, whether it’s a mattress or can opener or an Uber driver, a five-star rating simply means “nothing disastrous happened,” says Nikhil Garg, a doctoral candidate at Stanford University.