There's a basic paradox worth noting. As I've often described, every audience member is a "cognitive miser." Faced with an extraordinary amount of issues to track on a daily basis, it is actually quite reasonable for citizens to rely heavily on short cuts such as values and media frames to reach a decision about a policy debate. This natural human tendency leads to a complex scientific society where citizens often "go without data" in arriving at political and personal choices.
Of course, this often frustrates scientists who believe that an ideal public is one that is scientifically well-informed. Yet scientists in their approach to public engagement are often not much different from everyday citizens, as scientists in crafting messages and strategies also "go without data." Instead of pairing with social scientists who understand audiences and how messages are interpreted and re-interpreted across the media system, there is a gut level reaction that the best practice is to always just "get the facts out there."
This tendency, however, is changing, as several science-related organizations are adopting innovations and new models for public engagement. See for example the Coalition for the Advancement of Medical Research, 2009: Year of Science, Randy Olson's wonderful Flock of Dodos, recent and upcoming AMS Senate briefings, this Biosciences editorial, and Scientists and Engineers for America.