RUH Captcha helps filtering out all robot attempts to register/comment.
As of text question-based captchas, I have strong feeling they are in the past - Mr. Turing started the battle with bots more than 50 years ago (please see http://en.wikipedia.org/wiki/CAPTCHA). Can you imagine how many P.H.D.'s were made from this topic since then?:) So, what can we do today to prevail? IMO, we have to use cutting-edge technologies to be one (or, better, two) step ahead of bot-writing people.
Thank you for the link, it is very interesting technique. The only disadvantage, IMO, is that it tells the User what to do in plain English, it might be a weak spot. My method and the code don’t use any meaningful words which can be used as a clue how to solve the puzzle.
I believe that most of these comments are about reCAPTCHA (i.e. text-based CAPTCHA) because of difficulties in decifering the scrambled text even for humans. Although, in order to be more tolerant to the people, the plugin might be activated only for initial registration, leaving comments either unprotected or choosing another, ‘lighter’ CAPTCHA for them.