[thinkzig]

While you're right that all CAPTCHAs are annoying, the CAPTCHA ads are a whole different level of annoying. I think you'd lose more goodwill than you'd gain in money from doing this.

[Herwig]

depends, I believe it will depend on what the user has to type.

[michael_dorfman]

I disagree. I'd find an ad in my CAPTCHA to be sleazy regardless of what I had to type. It's a bad idea, full stop.