Amazon Prime Day kicks off midnight PST on Monday and lasts for two full days for the first time. While you're researching what to buy this year, there's an aspect you should keep in mind: Whether the Amazon reviews you're reading are legit.
On Tuesday, members of Congress wrote a letter Amazon CEO Jeff Bezos demanding to know what the company is doing about deceptive ratings and reviews ahead its Prime Day, which generates more than $4 billion in sales for the e-commerce giant, according to last year's numbers.
There are methods in place: Amazon uses artificial intelligence and a team of investigators to block and remove inauthentic reviews 24 hours a day, seven days a week, it works with social media sites to stop inauthentic reviews at the source, it pursues legal action to stop offenders and it's constantly improving these systems, an Amazon spokesperson tells CNBC Make It.
But still, fake reviews on the site – where sellers pay people or use bots to drum up phony positive reviews about their products in an effort to influence Amazon and Google rankings as well as consumers – are on the rise.
According to data from Fakespot, a website that uses artificial intelligence to help consumers determine the reliability of online reviews, fraudulent reviews on Amazon have climbed from 16.34% last June to more than 34% this June in all product categories. And in April, a probe carried out by U.K consumer group Which?, found tens of thousands of fake five-star reviews on products listed on Amazon.
(The problem has been intensifying since Amazon began to court Chinese sellers in 2015, according to data from Fakespot data. Amazon plans to pull its third-party services on its Chinese website starting on July 18, two days after Prime Day ends.)
There are some things you can do to try and distinguish the fake reviews from the authentic ones though, according to Fakespot COO and co-founder Robert Gross. Here are his top five tips to help spot fake reviews.
Electronics and gadgets are some of the most popular things sold on Amazon Prime Day; they're also the categories where Gross sees the highest percentages of fake reviews, particularly for Bluetooth headsets, cell phones and accessories and electronics. Ahead of Prime Day, many sellers in these categories aggressively create fake reviews to be "prominently displayed next to deals." In other words, if someone looks at a Prime Day deal and starts searching for similar products, the ones that use fake reviews aggressively will pop up in the product search results page, he says.
Gross says a big red flag that a product may have fake reviews is an "unnatural" distribution of five-star ratings. If a product from a seller that you've never heard of has several hundred reviews, and those reviews are all five-star, you should question their authenticity.
Even if a product has a large majority of five-star reviews and only a couple of one-star reviews, it's worth questioning. In that case, read the one-star reviews, as they are more than likely real, according to Gross' findings.
He also says customers should look for products that have a variety of ratings, including three or two-star reviews, because no matter how good a company is, not every product or customer experience is going to be perfect.
One of the most surefire ways to catch a fake review, says Gross, is to look at its language. If the reviews are very short and provide no details (like "good product," or "great company") there's a good chance it's fake, based on Fakespot's data over the last year.
Also look out for multiple reviews that have similar language to each other, says Gross, as some sellers create fake reviews using a variation of their company's marketing copy.
Gross says that Amazon and other e-commerce sites have gotten into the bad habit of showing consumer reviews that it deems to be the most relevant, not the most recent.
"These are usually the first reviews a consumer will see, and sometimes they are years old. Other times these reviews have been upvoted [by likes or comments] by fake review farms to push them to the top" he says.
Gross advises consumers to sort the reviews by "most recent" to get a better idea where the company or product stands today.
Gross says while Amazon's "Verified Purchase" tags are intended to help customers identify which reviews are legitimate, they have been taken over by fake reviewers and sellers, "to the point of being useless," he says.
"Verified purchase tags are easily gamed by fake reviewers and sellers that use them. They will typically ask the reviewer to buy the product and leave a five-star review. Once the five-star review is left, it will be labeled as from a verified purchaser. The seller then sends the 'buyer' a gift card for the amount or a little more to compensate them for the fake review," he says, adding that consumers shouldn't rely on them for authenticity.
An Amazon spokesperson tells CNBC Make It platforms like Fakespot cannot concretely determine the authenticity of a review "as they do not have access to Amazon's propriety data" and calls such companies "inaccurate" and biased toward distrust of Amazon and other stores.
"That is not to suggest that there aren't bad actors; we are aware of bad actors that attempt to abuse our systems and we continue to invest significant resources to protect the integrity of our reviews," Amazon says.
Fakespot refutes Amazon's claims of being inaccurate and says its artificial intelligence driven system does in fact have all the data necessary to detect fake reviews. Since 2015, Fakespot says it has analyzed more than 4.25 billion reviews from ecommerce platforms including Amazon, Walmart, Sephora and BestBuy.
Of course, even if reviews are fake, that doesn't mean a product is bad or good. And Gross points out that Fakespot does not analyze whether a product is good or bad either, only the quality of the reviews. However, if a consumer has never heard of the seller or company, they should do their own research before buying, he says.
"A good deal is not always the best product," he says.
This story has been updated to include statements from Amazon and Fakespot.
Like this story? Like CNBC Make It on Facebook.