Two things I've seen at my current job:
Inappropriate job titles
We wanted to hire a senior level system admin to do manage our development/production environment. The job also required implementing new security measures for HIPAA. Anyway, the job title was 'Director of Hosted Systems and Security' because half of the technology department is made up of directors. The resumes we got were from people with a ton of high level experience. One guy managed the server farm for MacDonalds and had not been hands on in years.
We were getting nowhere, because all of the people HR was bringing in for interviews had been hands off management types. I posted the description under a different title. I knew a lot of network engineers/sys admins from my previous job and one of them saw it and applied. I had reached out to a couple of people directly from my prev job, but no one wanted to make any moves.
Inappropriate job responsibilites
We needed to find a front end developer for our department's projects who could also do projects for our Client Services and Marketing departments. The job description we posted kept requiring java skills, even when that's not what we really needed. Sometimes HR thinks that all of the tech people interchangeable and should have the same skills.