TBH, I had decent results with the most trivial "3+4=" style CAPTCHAs. I know some sites where there's even only a single, hard-coded question/answer. In the

TBH, I had decent results with the most trivial "3+4=" style CAPTCHAs. I know some sites where there's even only a single, hard-coded question/answer. In the world where it's not about scaling to infinity, you're not getting targeted attacks, you're getting stupid bots that pummel every site thinking it's a WordPress install from 2007 and anything different is enough to scuttle it. By the time your service is popular enough to justify building a focused bot or tossing low-wage workers at it, hopefully you have the revenue in to finance something more sophisticated.