I've tried to protect a couple of Intents with a simple confirmation, using the form in the developer console. I keep finding that when Alexa doesn't get a good match to the intent samples, she picks which ever intent is most irritating. I rarely get FallbackIntent.
So when I invoke the intent (intentionally) I get the confirmation request I entered on the form. "Yes" proceeds to perform the intent. "Cancel" seems to drop it, but "No" seems to have it go ahead anyway.
Am I missing a trick?