The more important concept to keep in mind is that you want to choose keywords that best relate to the content present on a web page and on a website; if you don't have a dog food comparison matrix, then don't bother including comparison-related keywords; you are misleading your users, and certainly not fooling Google. So in an ideal world, you do have a comparison section, a reviews section, and a rankings section, housed on different pages or sections of your site, with each one tagged with the appropriate keywords. Correspondingly, your SEO and PPC search engine marketing efforts should that content by driving review keywords to the review pages and so on.
SEO may generate an adequate return on investment. However, search engines are not paid for organic search traffic, their algorithms change, and there are no guarantees of continued referrals. Due to this lack of guarantees and certainty, a business that relies heavily on search engine traffic can suffer major losses if the search engines stop sending visitors. Search engines can change their algorithms, impacting a website's placement, possibly resulting in a serious loss of traffic. According to Google's CEO, Eric Schmidt, in 2010, Google made over 500 algorithm changes – almost 1.5 per day. It is considered a wise business practice for website operators to liberate themselves from dependence on search engine traffic. In addition to accessibility in terms of web crawlers (addressed above), user web accessibility has become increasingly important for SEO.