I lol'd at this captcha test from craigslist. This is probably why other captcha implementations stick to nonsense words instead of using real words.

(Also, I tried the audio captcha. Those things are hard! It played a clip from a staticky movie soundtrack, and asked me to type the 20 word phrase the guy had said, which included the proper names of characters in the movie which I couldn't spell. I guess I'm not a person!)