Update: Demo now requiring an extra 'confirmation' step. It seems that FB starts requiring a confirmation of the like after a while - perhaps when a ratio of 'Likes' vs 'Un-Likes' is hit. This has been hit much sooner on the demo than on an 'evil' site since everyone has been alerted to the trick and thus knows to 'unlike'! Statement from Facebook developer here.
(glaub protecus brauch mal nen Like button)