Many years ago, my manager told me about a recruiting trip he made. In response to a large number of job applications submitted from a city where a major competing software company had its offices, a small group of Microsofties travelled to that city to interview those applicants and hold a mini-job fair, so that other interested parties could also show up and interview for positions.

When the company learned that Microsoft was coming to interview people, they called an emergency meeting which all their top programmers were required to attend, timing it to coincide with the job fair. The theory must have been that if their top programmers are at the emergency meeting, then they can't go to the job fair. Problem solved.

Well, except that the plan backfired. Sure, all the good programmers didn't come to the job fair, but it also told the interviewers which of the applicants were the good ones: They were the ones who didn't show up for their interviews!