I see one forum network in particular that is using some code to insert keyword/search phrases on the fly. By search phrases I mean a list of the most popular keywords that people are clicking through from SERPs to find the page. Clicking on one of these keywords brings you to a Google custom search of that keyword of the site. This is obviously only there for the search engines to dynamically put keywords on a page. My question is, how has Google and others not penalized these sites? Is there a chance that this is actually good in some way? What am I missing here?