agree^. They have their own interest in mind. The client (your potential employer) pays them a certain percentage of the position's base salary if they successfully place a candidate, so for staff pharmacist or manager/supervisor/DOP positions, this represents a significant commission for them. I have had numerous bad experiences with headhunters for being misleading in their descriptions (hospital was actually 70miles farther than advertised, staff positions advertised as clinical or decentralized positions, advertised salary range was 15K over the actual) and lying in order to pressure me into taking a bad offer/ position. Don't expect them to be 100% forthcoming with you.
That being said, there's nothing wrong with using them per se, especially if you're in a "tight" geographic job market, because I know several hospitals in my area that prefer to use recruiting agencies rather than posting them themselves on their job pages (even for permanent positions), meaning applying to a job ad without knowing the exact hospital may actually alert you of opportunities you wouldn't have known of otherwise.
As long as you go into it knowing that a) there is no commitment until you sign an offer letter and b) you have to do what's best for yourself at the end of the day, you should be fine.