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Review Brigades

December 2nd, 2016

Brigading is a term used when online trolls group together to flood another site (or subsection of a website) with their message.  On Amazon, this happens when a product is quickly flooded with negative reviews, often politically motivated, and likely by reviewers who have not actually used the product or read the book.

We’ve seen some pretty high-profile examples in the media recently:  

Here’s a few more lesser known examples:

So How Can We Detect Brigading?

There’s a few tell-tale signs of brigading that are very easy to notice once we’ve run a report on the reviews:

1. Rating from Unverified Purchasers is much lower than the rating from Verified Purchasers


Since the brigaders will not go out of their way to purchase the item before leaving a nasty review, you’ll often see an unusually high amount of unverified purchases, which are much lower on average than the verified purchase reviews.  

2. High number of Deleted Reviews


A high number of deleted reviews with a low average rating does not mean that Amazon is taking sides and trying to silence a group of people.  Amazon is simply doing their job of removing reviews from people who obviously have not used the product.

3. Lots of negative reviews appearing all at once


Our Rating Trend test can be highly telling of when the brigades happen.  Usually, brigades are organized on different sites outside of Amazon (Reddit, Facebook, Twitter), and then inspire a flood of reviews all around the same date.  If the rating from reviews on High-Volume days is considerably lower than the rating from reviews on Normal-Volume days, it can be a sign of brigading.

4. Lots of reviews from Suspicious Reviewers


Because many who participate in brigades aren’t regular Amazon reviewers, brigades often trigger a lot of warns or fails for our Suspicious Reviewers test.

This test has four parts, and any or all might be a warning sign of a brigade:

  • One-Hit-Wonders: Reviewers who have only written one review on Amazon.
  • Never-Verified Reviewers: Users who have never left a “Verified Purchase” review.
  • Single-Day Reviewers: Those who have posted all their reviews on one day.
  • Take-Back Reviewers: Accounts who have reviews that have been deleted previously.

Our algorithm will look at these red flags and warn you about possible brigades.


While our warning is wonderful tool to help you quickly identify when a product is being brigaded, it’s always a good idea to look through the rest of the report yourself and ultimately make your own decision about the authenticity of the reviews.

  • evo34

    How about the opposite — a flood of fake positive reviews? DO you have an alert for that?

    • That’s pretty much what our standard report is trying to look for.