Behind Box-Office Sales: Understanding the Mechanics of Automation Spam in Classifieds.

In spite of being detrimental to user experiences, the problem of automated messages on online classified websites is widespread due to a low barrier of entry and limited enforcement-of-rules against such messages. Many of these messages may appear legitimate, but turn into spam when they are posted redundantly. This behavior drowns out other legitimate users from having their voices heard. We label this problem as automation spam – legitimate messages that are posted at a rate that overwhelms normal posts. In this paper, we characterize automation on a popular classifieds website, Craigslist, and find that 2/3rd of the posts with URLs are automated. Automation is most prevalent in categories dominated by businesses, such as Tickets, Cars by Dealer, and Real Estate, with 67–92 % of the posts with URLs exhibiting automation. Even in categories with less automation, intermittent automation still overwhelms non-automated users, demonstrating that no category is safe.