(showing up in non-paid results) links is less emphasized in today’s search engines but remains clear). @Rutz2011 demonstrated how tying paid search results to generic search terms might increase the success of a branded paid search.

The search and engage campaigns (see section \[Sec:search\]) discussed in the present paper are different. They don’t try to increase visibility by buying paid results. These represent the dark side of search engine-based advertising, whereby they try to directly manipulate the organic links.

It was envisaged [@Zhang2013] that the identification of the key influencers on social media could be crucial for effective viral marketing—but with the gray marketing techniques presented here, influence is attempted to be created directly, albeit artificially.

It was also envisioned that customer-generated content on blogs, etc. would be crucial for promotional activities—in the present paper, campaigns seeking to manufacture legitimate-looking customer content are analyzed. In other words, these campaigns, albeit unethical, are sometimes the effective counterparts of hard-to-operate social media marketing tactics, or in other words, they are controversial shortcuts to followers and likes and brand-friendly social content.

Confessore et al.’s recent work reported on in the New York Times [@Confessore2018] covered a very similar theme to this article, but 