Whiles many of us love visualizations, sometimes we forget that a model is not reality. If "do no evil" fails in practice, someday someone may write a documentary called How to Lie with Video Statistics, or maybe Lies, Damn Lies and Data Visualization. As a temporary counter weight to cynics armed with reams of biased analysis, here's Peter Donnelly on How juries are fooled by statistics from TED:
Update: of course someone else already alluded to the famous book How to Lie with Statistics -- see How NOT to lie with visualization by Rogowitz, Treinish, and Bryson from Computers in Physics (1996). Plus, there's How To Lie With Charts by Gerald E. Jones -- and Lies, damned lies and statistics (about TEDTalks).