The 99% effective statistic came from the author of codinghorror.com. His CAPTCHA for every comment is a single static image of the word "ORANGE" in a slightly stylized but plainly readable font. I've seen other bloggers claim that simple addition puzzles are almost 100% effective as well (at least, they were when they were introduced).
I think that spammers simply don't want to create a special case handling of every site they come across.
I think in less than 5 years, a botnet will be able to participate in discussions in a way that is nearly indistinguishable from humans. If a robot posts better-than-average commentary, do you care if it is a real human or not?
Interesting. Perhaps spammers are just lazy -- if they aren't following the latest captcha techniques. I still find those examples incredible, but as long as they work, happy.
And to answer your question, no. When you play chess with a strong computer, or a living grandmaster, both are formidable opponents playing the same game. Talking to an educated person and a strong AI capable computer would be participating in the same discussion. (I don't know if this is objectionable but it makes perfect sense to me; if you see otherwise, do explain.)
However, if and when that happens, the world is going down a wildly different path, and that problem you point out will be a minor one, compared to some dramatic job cuts it will likely bring about and the businesses that it wipes out.
I think that spammers simply don't want to create a special case handling of every site they come across.
I think in less than 5 years, a botnet will be able to participate in discussions in a way that is nearly indistinguishable from humans. If a robot posts better-than-average commentary, do you care if it is a real human or not?