Invalidating cache issues

We seem to have an issue of the LTM hanging on to cached content for long periods of time. We have quite a few RESTful apps that our clients connect to for API access. Of course these return very dynamic reponses to their posts. However, the LTM caches all of it. We have tried using cache-control no-cache and that seems to do nothing. I saw there was an article on the LTMs not respecting multiple cache-control statements, but we are only using cache-control once in responses.

Any ideas why the LTM is hanging on to things like this?

EDIT: Here is a for instance. We embed Pinglish

https://github.com/jbarnette/pinglish

into our pages for monitoring purposes. Note it outputs the time for each request and even that is cached.