  Purpose: This research investigates controversial online marketing techniques
that involve buying hundreds or even thousands of upvotes, likes, comments,
etc.
  Methodology: Observation and categorization of 7,426 campaigns posted on the
crowdsourcing platform microworkers.com over a 365 day (i.e., yearlong) period
were conducted. Hypotheses about the mechanics and effectiveness of these
campaigns were established and evaluated.
  Findings: The campaigns contained a combined 1,856,316 microtasks, 89.7% of
which were connected to online promotion. Techniques for search engine
manipulation, comment-generating in the scale of tens of thousands, online vote
manipulation, mass account creation, methods for covering tracks were
discovered. The article presents an assessment of the effectiveness of such
campaigns as well as various security challenges created by these campaigns.
  Research limitations: The observed campaigns form only a small portion of the
overall "black market". This is due to invite-only campaigns and the presence
of alternative, unobservable platforms.
  Practical implications: The findings of this article could be input for
detecting and avoiding such online campaigns.
  Social implications: The findings show that in some conditions tremendous
levels of manipulation of an online discourse can be achieved with a limited
budget.
  Originality: While there is related work on "follower factories" and
"click/troll farms", those entities offer complete "solutions" and their
techniques are rather opaque. By investigating a crowdsourcing platform, this
research unveils the underlying mechanics and organization of such campaigns.
The research is based on a uniquely large number of observations. Small, cheap
campaigns, the manipulation of less significant platforms is also included,
while the related work tends to focus on mass, politically motivated efforts.
