I recently posted a job opening on oDesk (designer / developer job), and put a simple instruction in there. In the middle of the job description, I wrote:
Also, you must tell me what 4+3 is, so I know you’ve read this entire description.
It’s so easy now to weed out those applicants who just paste their cover letter without any regard as to what the job entails. oDesk even has a reason for rejection, which goes like: “Applicant ignored instructions in job description”. I used that a LOT when rejecting applicants for this job.
If you can’t follow this simple instruction, how do I expect you to follow instructions on real tasks that I assign you?