Review sites are generally supported by advertising
A review site is a website on which reviews can be posted about people, businesses, products, or services. These sites may use Web 2.0 techniques to gather reviews from site users or may employ professional writers to author reviews on the topic of concern for the site. Early review sites included Epinions.com  and Amazon.com.
Review sites are generally supported by advertising. Some business review sites may also allow businesses to pay for enhanced listings, which do not affect the reviews and ratings. Product review sites may be supported by providing affiliate links to the websites that sell the reviewed items.
With the growing popularity of affiliate programs on the Internet, a new sort of review site has emerged - the affiliate product review site. This type of site is usually professionally designed and written to maximize conversions, and is used by e-commerce marketers. It's often based on a blog platform like Wordpress, has a privacy and contact page to help with SEO, and has commenting and interactivity turned off. It will also have an e-mail gathering device in the form of an opt-in, or drop-down list to help the aspiring e-commerce business person build an e-mail list to market to.
Because of the specialized marketing thrust of this type of website, the reviews are not objective.