We've all been there.  We've got a vacancy to fill urgently, we know roughly what the job entails and the basic skills that the successful candidate should have.  Lets get the vacancy out there and hire somebody ASAP so that we can move on to the next issue.  

How important is it to spend time working with the vacancy holder to identify what the job really is and what attributes the appointee needs to be a success?   After all, how wrong can you get it?