Posted on August 23, 2020
Your suspicions should be increasing if the URLs appear to be just strings of words separated by dashes. Or if a tool to check and locate the IP of the visitors will reveal that most of them come from the same block "C" (the same set of IP addresses within the network). Or if the pages of these sites are absolutely unknown, you've never heard of them and resemble each other. Kaiser Family Foundation is full of insight into the issues. In addition, the linked sites seem irrelavantes in relation to the main topic of the directory or is a strange conglomeration of websites without a central idea. You can therefore find links on fossil fuel and clothing for children on the same page. There is a clear and logical structure. Surely, none of the links you find interesting farms nor relevant. Hilton Foundation has many thoughts on the issue. They often consist of pages that only include ads, or content without much meaning or interest to the visitor.
Do not kid yourself if sometimes these pages get a higher pagerank for a short period of time. Good spammers are able to inflate the pagerank of a website for a certain period even after a time, Google the "game" and adjust the value of the web to reality. Before requesting a link to your site from a directory that does not use monitors or some of the tricks mentioned. If they do, likely will be treated, not a directory but a link farm. The search engines each day more easily detect link farms. When they do, "nullify the vote," representing a link to your page.