Beware of snipers: Online merchants being hammered by phoney reviews on Amazon
Mike Molson Hart, who sells toys on Amazon's marketplace, realised earlier this month that something was amiss.
His company's popular, disc-shaped, plastic building set, called Brain Flakes, had dropped precipitously in the ranks of Amazon's best-selling toys.
He suspected that he was the victim of 'sniping', when one merchant sabotages another by hiring people to leave critical reviews of their goods and then voting those reviews as being helpful.
Maintaining order on Amazon - where two million merchants compete to win billions in business from 300 million shoppers - has become a running problem for the online giant.
"This stuff has been going on non-stop since we started selling on Amazon," said Mr Hart, president of Viahart in New York City. "It's still the Wild West."
Amazon said it "does not tolerate fraud or abuse of our policies". The company said it was "constantly working to improve the ways we detect and prevent abuse from impacting customers". Amazon said it suspends or blocks "bad actors" suspected of illegal behaviour or infringing on others' intellectual property rights.
US online spending in November and December will top $107bn (€89.6bn) this year. Merchants who are targets of sniping stand to lose the most.
Manipulation of reviews has been increasing over the past few months and Amazon doesn't appear to be fixing the problem, said Chris McCabe, a former employee who now runs a consulting business to help Amazon merchants.
"It's a massive problem and until it's more publicly known, I don't think they'll do anything about it," said Mr McCabe.
The threat to Amazon is faith in its customer reviews, which it has used to boost confidence of shoppers buying something online that they may not have touched or seen first-hand.
Two years ago, Amazon filed lawsuits against more than 1,000 people, who it alleged were writing fake product reviews for money.
The Seattle-based company also clamped down on "incentivised" reviews written by people who received free or discounted products.
However, the lawsuits and crackdowns are proving to be little more than speed bumps to those looking to game the system.
Product-review forums on Facebook are a common place where merchants can search for accomplices, sending them Amazon gift cards, so they can get a free item in exchange for a positive review, while eluding detection from Amazon.
Another scam is to relentlessly click on the Amazon advertisements of a competitor's product without actually buying anything, which drains their advertising account.
Mr Hart said he's frustrated with Amazon's response to his complaints about his products' reviews getting manipulated. He fears retribution for speaking up, but the stakes are high as he could lose $1m (€850,000) in sales this season.
Amazon has said that it is examining his concerns, but Mr Hart said: "Amazon knows about it and it has become their policy to not do anything."