1. A method of worker quality control in crowd sourcing tasks, the method, comprising: selecting a job distributed through a job distribution platform for workers to work on to generate a test task, the job being associated with a known correct result; associating a manipulated result, known to be an incorrect result for the job, with the job to generate the test task; presenting the job with the manipulated result as the test task to a worker for evaluation of work quality of the worker; wherein, the job distribution platform crowd sources tasks online to workers to work on via their respective computing devices.