Correction: The original version of this story showed an image which included information from a newsletter sent by Amazon to frequent reviewers. It was not made clear to the person who provided the newsletter to NPR that the information would be published as part of the story. The image has since been removed.
You're on Amazon.com. You're buying, say, a toaster, and you're checking out the customer reviews. You assume the people writing these reviews are people like you — people who wanted a toaster, went online and bought one. As it turns out, a lot of reviews on Amazon are written by people who are nothing like you. They're written by elite reviewers who are sent free merchandise to review products. In other words, it's possible that the guy reviewing that toaster you're looking at wasn't in the market for a toaster to begin with and didn't pay a cent for it.
As of Tuesday, Michael Erb was the No. 1 customer reviewer on Amazon. He has reviewed everything from doorbells to travel mugs to toothbrushes. "I have so many Bluetooth speakers, it's ridiculous," he told me. "I've got enough lithium ion batteries in my house to blow up a city block."
As Erb has risen up the ranks among Amazon reviewers, the stream of free stuff has grown because manufacturers have started sending stuff directly to him to review. "I have to admit it has probably caused a little bit of a strain on my marriage because my wife goes crazy," he says. "Literally every other day there's UPS boxes piled up at the door."
Erb is a member of Amazon Vine, an invitation-only program for the site's top reviewers. At least once a month, Amazon sends Erb a list of products. He gets to choose any two items from the list. "My only obligation is that I need to write a review of those two items within 30 days," Erb told me. "And I get to keep the items after I review them."
Like other top reviewers, Erb says he reviews so many products because he likes sharing his knowledge and getting feedback from other customers. Amazon also fuels competition among reviewers by making their rankings public. And top reviewers do get a lot of free stuff.
Through Vine, Erb has received everything from cheap earbuds (worth a few bucks) to multifunction laser printers (retail price about $500) to a spin bike (worth almost $1,000). In all, he says, he's received thousands of dollars worth of merchandise through the program.
Amazon does have some rules on the freebies. Erb can't sell the products or give them away. In fact, Amazon can ask for the stuff back any time it wants. But in the five years Erb has been in the program, Amazon has never asked for anything back.
Anindya Ghose, an NYU professor who studies consumer reviews, said Vine members might review things more positively than people who had to pay for their stuff.
"As humans we are hard-wired to give in to this sort of enticement where if you continuously get things for free, then you're more likely to be biased positively than biased negatively," he said.
But Julie Law, an Amazon spokeswoman, told me Vine reviews have fewer stars, on average, than other reviewers on the site. (Correction: An earlier version of this sentence said Law said Vine reviews are more negative than other reviews.)
Law said the Vine program was created to deal with some of the inherent challenges in customer reviews. For example, if someone has a bad experience with shipping or a particular seller, their review may be more about that specific experience than about the product itself. So Amazon works with the site's most trusted reviewers to populate the site with more useful reviews. Even a product with negative reviews sells better than a product with no reviews at all.
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