If you're having trouble getting your HITs done or ensuring quality work on Turk, MobileWorks (YC S'11) is essentially a better version of Turk that takes care of these things for you. (Disclaimer: I'm an engineer at MobileWorks.) Your experiment with oDesk is interesting, but I can't help but feel that this sort of microtask work is not was oDesk was built for.

We're crowd researchers who spend our time working on methods for routing tasks to qualified workers and QAing work. We aren't a wrapper on top of Turk -- we're our own platform and we employ our own workers. You just push HITs to our API and we take care of quality control and worker management for you.

If you're interested, email me at lionel @ (my company) .com and I can help you get started.