First, thanks for writing. I'm glad you asked this, too!  Noooooo, I don't recommend these sites as places to just post a resume. If I hear that this is someone's strategy, I would recommend against it. Quite the opposite.  These sites are "sources". They are in response to the crap, I mean, excuse that "there are no jobs out there.". When I coach people who don't know what they want to do next, I say "go to Monster.com or Indeed.com and narrow down to 10 job description examples. Figure out what is in common with them, why you chose them and, as a result, write out your goal for your job search."  I don't recommend they apply just yet, but figure out what function you desire by doing research on these great sites.  

Thank you, again!
Dana