What I'm far more concerned about with totally fake job listings are the foreign placement agencies that harvest data from resumes and interview native citizens to get information and terminology to prop up their foreign candidate's resume's over the native candidates.
The placement agency makes their candidates look far better based on the information mined from the resumes and interviews, they learn how to speak about technology they don't fully understand. The employee gets a placement, the Business gets a cheap H1B indentured worker, and the Agency gets a fatter commission for selling a "more qualified" candidate.