Using Uses in AppController
Don't do it.
Or maybe there's a better way to do it. The problem I ran into was that I had some Model code that needed to run on every page. So, I thought that I'd add the model to the uses variable in the AppController.
The problem with that, as it turns out, is that none of the controllers overrode this property. This meant they couldn't access their models properly. This made leaving a comment here within the last 12 hours impossible. Whoops!
If ever there was a reason for me to get into test-driven development, this was probably it.