If you've ever applied for an H-1B then you know how easy it is to abuse the prevailing wages. The process to evaluate the skills of the applicant is simply filling out a form online for their experience level, job title, and location. Give it a test here: http://www.flcdatacenter.com/OesWizardStart.aspx It's very easy to game their job title and location to lower the salary.
Here is the law firm Cohen & Grigsby advising other employers in running classified ads with the goal of NOT finding any qualified applicants, and the steps they go through to disqualify even the most qualified Americans in order to secure green cards for H-1B workers: https://www.youtube.com/watch?v=TCbFEgFajGU This seems like clear fraud. The issue I have with H-1Bs is when companies lie/cheat/commit fraud to outsource jobs that Americans do want and are qualified/willing to do, all for the sake of driving down wages.