In its continuing campaign against fake and biased product reviews on its platform, Amazon has made a significant change to its Community Guidelines that bans reviewers from receiving free or discounted products in exchange for reviews.

Called incentivized reviews, they were previously allowed by Amazon so that new products will gain traction in the online marketplace, as products without any reviews or sales could easily be buried under other listings in search results. The only requirement was that the reviewer should disclose that he or she received the product for free or acquired it with a discount.

In a blog post by Amazon VP of customer experience Chee Chew, he wrote that starting now, incentivized reviews will now only be allowed through the Amazon Vine, which is a program launched several years ago that carefully facilitates such reviews.

Under Amazon Vine, the company selects and invites helpful and trusted reviewers on the platform to post their opinions regarding new and upcoming products. The seller of the product does not get to choose the reviewer, with Amazon adding that it does not push for positive ratings or try to influence what the reviewer will write.

Chew added that the company is looking to increase the usefulness of the Amazon Vine program going forward, with Amazon to release the details on such improvements as they are implemented.

The updated guidelines will apply to all product categories except for books, with Amazon to continue the practice of sending advance copies of books to reviewers. All other reviews in exchange for other forms of compensation are not allowed by Amazon.

While incentivized reviews, in theory, still allow reviewers to express their true opinions, these reviews have tended to be biased in favor of the product that was involved. This could be due to several factors, including the seller choosing less critical reviewers and users thinking that they may no longer get offers for incentivized reviews if they do not give a positive one.

The ban on incentivized reviews continues Amazon's crackdown on fake and biased product reviews on its platform. In June, Amazon shifted away from attacking websites that offer to post five-star recommendations for products on its website in exchange for cash and instead started to file lawsuits against the sellers that buy such fake reviews.

To further improve the customer experience, Amazon also later launched initiatives to reduce counterfeit products on the website, including a one-time fee of up to $1,500 for sellers looking to sell products from major brands and the requirement for paperwork that confirms the authenticity of branded products.