The Cache Refresh Test
The image below is an indicator whether you have successfully emptied your cache. The contents of the image changes after it has been reloaded from the server. Experiment with your cache by refreshing this page several times and clearing your cache in between.
Troubleshooting
Browser Cache can behave pretty unpredictable. If the image changes on every refresh (even the not-forced refresh) it could be that your cache was disabled. If the image never changes you have a very stubborn browser, you might want to restart your browser to see if this helps.