CHEATING: How merchants use Facebook to flood Amazon with fake reviews.

Many of these fraudulent reviews originate on Facebook, where sellers seek shoppers on dozens of networks, including Amazon Review Club and Amazon Reviewers Group, to give glowing feedback in exchange for money or other compensation. The practice artificially inflates the ranking of thousands of products, experts say, misleading consumers.

But the ban, sellers and experts say, merely pushed an activity that used to take place openly into dispersed and harder-to-track online communities.

There, an economy of paid reviews has flourished. Merchants pledge to drop reimbursements into a reviewer’s PayPal account within minutes of posting comments for items such as kitchen knives, rain ponchos or shower caddies, often sweetening the deal with a $5 commission or a $10 Amazon gift card. Facebook this month deleted more than a dozen of the groups where sellers and buyers matched after being contacted by The Post. Amazon kicked a five-star seller off its site after an inquiry from The Post.

The kicker? The Post in question is Jeff Bezos’ own Washington Post.