Client is using WPTouch for their mobile site (until they can budget for responsive design), and we had an interesting issue this morning. One of the pages was showing the mobile version on desktop, and it would not switch to "Desktop" when you clicked the link. When I went in to WP Quick Cache and cleared the cache, it was fixed.
Thought I'd bring this up, because I can't think of any reason the mobile version of a page might be cached on a desktop? Is it possible that WPTouch is not compatible for some reason?