Coding Horror : CAPTCHA effectiveness

There’s a popular misconception in technical circles that CAPTCHA has been « broken ». Some people actually believe that spammers can now « fairly easily » write scripts which use advanced optical character recognition to automatically defeat any online CAPTCHA form.
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The comment form of my blog is protected by what I refer to as « naive CAPTCHA », where the CAPTCHA term is the same every single time. This has to be the most ineffective CAPTCHA of all time, and yet it stops 99.9% of comment spam. I can count on two hands the number of manually entered comment spams I’ve gotten since I implemented it.