The “gas tax holiday” ad that Hillary Clinton used had not one, but two anti-Clinton messages in it! A newspaper clip used in the ad was actually about “Troopergate”, an allegation that state troopers arranged sexual liaisons for Bill Clinton. The second an attack line against Clinton from an Obama ad. The article has the video and a screenshot.
http://www.eyesonobama.com/blog/content/id_16969/title_Breaking-Subliminal-Pro-Obama-messages-in-Clinton-campaign-ads/