title: Devise authentication: captcha necessary?
body: <p>I'm using the devise authentication plugin under rails 3. At the moment, I have disabled the email confirmation, so that sign up is really easy and fast.</p>
  
  <p>I'm wondering if some kind of captcha is necessary to protect the site agains bots. I would like to avoid having my database filled with fake users, although this couldn't do much harm to the system (except filling up the disks!).</p>
  
  <p>If a captcha is strongly recommended, is it also true if sign in/up is restricted to HTTPS? Do bots use HTTPS?</p>