Many blogging software packages automatically nofollow user comments, but those that don't can most likely be manually edited to do this. This advice also goes for other areas of your site that may involve user-generated content, such as guest books, forums, shout-boards, referrer listings, etc. If you're willing to vouch for links added by third parties (for example, if a commenter is trusted on your site), then there's no need to use nofollow on links; however, linking to sites that Google considers spammy can affect the reputation of your own site. The Webmaster Help Center has more tips on avoiding comment spam40, for example by using CAPTCHAs and turning on comment moderation.
QUOTE: “7.4.3 Automatically Generated Main Content Entire websites may be created by designing a basic template from which hundreds or thousands of pages are created, sometimes using content from freely available sources (such as an RSS feed or API). These pages are created with no or very little time, effort, or expertise, and also have no editing or manual curation. Pages and websites made up of autogenerated content with no editing or manual curation, and no original content or value added for users, should be rated Lowest.” Google Search Quality Evaluator Guidelines, 2017
It's wonderful to deal with keywords that have 50,000 searches a month, or even 5,000 searches a month, but in reality, these popular search terms only make up a fraction of all searches performed on the web. In fact, keywords with very high search volumes may even indicate ambiguous intent, which, if you target these terms, it could put you at risk for drawing visitors to your site whose goals don't match the content your page provides.
One common scam is the creation of "shadow" domains that funnel users to a site by using deceptive redirects. These shadow domains often will be owned by the SEO who claims to be working on a client's behalf. However, if the relationship sours, the SEO may point the domain to a different site, or even to a competitor's domain. If that happens, the client has paid to develop a competing site owned entirely by the SEO.