I am surprised issues of this kind have taken so long to surface:
Amazon is investigating claims that employees accepted bribes to disclose confidential data that would give sellers that use its marketplace a competitive advantage. The company confirmed the investigation following a report in the Wall Street Journal that Amazon employees, working through brokers, have sold internal sales data, the email addresses of product reviewers, and the ability to delete negative reviews and restore banned accounts. “We are conducting a thorough investigation of these claims,” an Amazon spokeswoman said.
These practices seem to be a particular problem in China, though not only. Here is more from Shannon Bond at the FT. Here is further coverage at Verge: “The WSJ also reports that it costs roughly $300 to take down a bad review, with brokers “[demanding] a five-review minimum” per transaction.”