While taking a look into a reported vulnerability in a WordPress plugin recently we noticed a rather glaring example of the use of fake reviews. First and foremost there were almost as many reviews as active installations of the plugin:
Unless the very few people using it really liked the plugin, the number of reviews is way out of line with other plugins (where there usually is one review per one hundred or more active installs).
The other big tip-off was that all the reviews occurred on one day (two days after the plugin was released):
One of those reviews was from someone who was supposed to have used it while running WordPress 1, which seems quite unlikely, to say the least.