When would this be useful? If your site has a blog with public commenting turned on, links within those comments could pass your reputation to pages that you may not be comfortable vouching for. Blog comment areas on pages are highly susceptible to comment spam. Nofollowing these user-added links ensures that you're not giving your page's hard-earned reputation to a spammy site.

Search engines may penalize sites they discover using black or grey hat methods, either by reducing their rankings or eliminating their listings from their databases altogether. Such penalties can be applied either automatically by the search engines' algorithms, or by a manual site review. One example was the February 2006 Google removal of both BMW Germany and Ricoh Germany for use of deceptive practices.[54] Both companies, however, quickly apologized, fixed the offending pages, and were restored to Google's search engine results page.[55]
QUOTE: “Some pages load with content created by the webmaster, but have an error message or are missing MC. Pages may lack MC for various reasons. Sometimes, the page is “broken” and the content does not load properly or at all. Sometimes, the content is no longer available and the page displays an error message with this information. Many websites have a few “broken” or non-functioning pages. This is normal, and those individual non-functioning or broken pages on an otherwise maintained site should be rated Low quality. This is true even if other pages on the website are overall High or Highest quality.” Google
Being ‘relevant’ comes down to keywords & key phrases – in domain names, URLs, Title Elements, the number of times they are repeated in text on the page, text in image alt tags, rich markup and importantly in keyword links to the page in question. If you are relying on manipulating hidden elements on a page to do well in Google, you’ll probably trigger spam filters. If it is ‘hidden’ in on-page elements – beware relying on it too much to improve your rankings.
Google asks quality raters to investigate your reputation by searching “giving the example [“ibm.com” reviews –site:ibm.com]: A search on Google for reviews of “ibm.com” which excludes pages on ibm.com.” – So I would do that search yourself and judge for yourself what your reputation is. Very low ratings on independent websites could play a factor in where you rank in the future – ” with Google stating clearly “very low ratings on the BBB site to be evidence for a negative reputation“. Other sites mentioned to review your business include YELP and Amazon. Often – using rich snippets containing schema.org information – you can get Google to display user ratings in the actual SERPs. I noted you can get ‘stars in SERPs’ within two days after I added the code (March 2014).
Do you regularly publish helpful, useful articles, videos or other types of media that are popular and well produced? Do you write for actual human beings rather than the search engine itself? Well, you should. Latest research from Searchmetrics on ranking factors indicates that Google is moving further towards longer-form content that understands a visitor’s intention as a whole, instead of using keywords based on popular search queries to create content.
Everyone knows intent behind the search matters. In e-commerce, intent is somewhat easy to see. B2B or, better yet, healthcare, isn't quite as easy. Matching persona intent to keywords requires a bit more thought. In this video, we'll cover how to find intent modifiers during keyword research, how to organize those modifiers into the search funnel, and how to quickly find unique universal results at different levels of the search funnel to utilize.

The SEO tools in this roundup provide tremendous digital marketing value for businesses, but it's important not to forget that we're living in Google's world under Google's constantly evolving rules. Oh and don't forget to check the tracking data on Bing now and again, either. Google's the king with over 90 percent of worldwide internet search, according to StatCounter, but the latest ComScore numbers have Bing market share sitting at 23 percent. Navigable news and more useful results pages make Bing a viable choice in the search space as well.
This is also where you can see Google's ML algorithms at work. Powered by Google Cloud Platform, the way Quick Answers and Featured Snippets are extracted gets increasingly smarter as Google introduces new innovations in deep learning and neural networks. These constantly evolving algorithms are baked into how the search engine surfaces information.
QUOTE: “I think there is probably a misunderstanding that there’s this one site-wide number that Google keeps for all websites and that’s not the case.  We look at lots of different factors and there’s not just this one site-wide quality score that we look at. So we try to look at a variety of different signals that come together, some of them are per page, some of them are more per site, but it’s not the case where there’s one number and it comes from these five pages on your website.” John Mueller, Google
Domain authority is an important ranking phenomenon in Google. Nobody knows exactly how Google calculates, ranks and rates the popularity, reputation, intent or trust of a website, outside of Google, but when I write about domain authority I am generally thinking of sites that are popular, reputable and trusted – all of which can be faked, of course.
QUOTE: “I’ve got a slide here where I show I think 8 different URLs you know every single one of these URLs could return completely different content in practice we as humans whenever we look at ‘www.example.com’ or just regular ‘example.com’ or example.com/index or example.com/home.asp we think of it as the same page and in practice it usually is the same page so technically it doesn’t have to be but almost always web servers will return the same content for like these 8 different versions of the URL so that can cause a lot of problems in search engines if rather than having your backlinks all go to one page instead it’s split between (the versions) and it’s a really big headache….how do people fix this well …. the canonical link element” Matt Cutts, Google

Either porn SC or Ads containing porn on non­Porn pages can be very distracting or even upsetting to users. Please refresh the page a few times to see the range of Ads that appear, and use your knowledge of the locale and cultural sensitivities to make your rating. For example, an ad for a model in a revealing bikini is probably acceptable on a site that sells bathing suits. However, an extremely graphic porn ad may warrant a Low (or even Lowest) rating.”
Google states, “News articles, Wikipedia articles, blog posts, magazine articles, forum discussions, and ratings from independent organizations can all be sources of reputation information” but they also state specifically boasts about a lot of internet traffic, for example, should not influence the quality rating of a web page. What should influence the reputation of a page is WHO has shared it on social media etc. rather than just raw numbers of shares. CONSIDER CREATING A PAGE with nofollow links to good reviews on other websites as proof of excellence.
The tools we tested in this round of reviews were judged on which do the best job of giving you the research-driven investigation tools to identify SEO opportunities ripe for growth, along with offering enterprise-grade functionality at a reasonable price. Whether one of these optimization tools is an ideal fit for your business, or you end up combining more than one for a potent SEO tool suite, this roundup will help you decide what makes the most sense for you. There's a wealth of data out there to give your business an edge and boost pages higher and higher in key search results. Make sure you've got the right SEO tools in place to seize the opportunities.

The existing content may speak to core audiences, but it isn’t producing many strong organic results. For example, the content header Capitalizing on the Right Skills at the Right Time With Business Agility may seem OK, but it doesn’t include a keyword phrase within striking distance. The lengthy URL doesn’t help matters. Extraneous words prevent any focus and the URL is bogged down by “business” and “agility” duplication:
Did you know that nearly 60% of the sites that have a top ten Google search ranking are three years old or more? Data from an Ahrefs study of two million pages suggests that very few sites less than a year old achieve that ranking. So if you’ve had your site for a while, and have optimized it using the tips in this article, that’s already an advantage.