Yes. The lower traffic your site is, the easier you can make the captcha. The truth is, most of us have pretty low traffic sites with no more than 100k hits per month, blogs for example. The key here is to have a simple but different captcha compared to the standard stuff. Pairing this strategy with a little bit of site-specific domain knowledge goes a long way towards discouraging trolls and idiots.

I think overall, bots would be negatively impacted by a more diverse captcha ecosystem even if the individual implementations are easier to crack. Spammers don't invest 10 or 20 minutes in cracking a domain-specific captcha system just so they can spam one single blog - they'd rather move on to thousands of sites that are protected by the same standard word reading puzzle. Of course, if your site rises into the upper strata of the web, you're also quickly entering a zone where the standard, hard-to-decipher image strategy isn't working so great anymore either.

Jeff from coding horror for a long time used a very very simple "CAPTCHA". You just had to enter 42 (if I recall correctly), and it was always just that, nothing random. It served him well, and he has a high traffic site (http://www.codinghorror.com/blog/2006/10/captcha-effectivene...)

And that the question randomizes pretty well. Otherwise posts could be automated.