There are very helpful tools out there to debug WPF applications in run-time like Snoop , WPF Inspector and Xaml Spy which allow you to sneak peek into running application and monitor property values, DataContext changes, routing events and even triggers switching.
But what I did not managed to find in any of them is the way how to monitor VisualStateManager (VSM) transitions between states on particular selected control in run-time.
Is there any tool that could help with figuring out why a control doesn't go into the particular expected state (considering absence of source code for this application/library)?

Update: The question is mostly about debugging compiled code, when you have no access to the source. For cases when you have access to source code here is pretty good explanation of one of the ways to go.