Every so often I receive an email message or phone call, sometimes from a friend, sometimes from someone I don't know, saying that his or her department has a job, here's what they're looking for, and can I spread the word and help them find someone who fits the bill?
If I wasn't sent the job ad, I look it up. Usually, the criteria that I was told are very different from those in the job ad.
I point out the discrepancy between the official ad and what they told me, and suggest that their job ads state the criteria they're really looking for. I also suggest that they advertise widely, and not just spread the word via the "old boy network" (even if it includes me). Put together a diverse hiring committee. Interview the people whose files best satisfy the criteria in the job ad.
They usually seem surprised by my advice.