Writing in Media Psychology, Markus Appel discusses a study where 63 Austrian college students who read a short about someone stupid then did worse on a test than a control group - they became more stupid - but the effect did not occur when the readers had to outline how they differed from the stupid character.    The stupid character was in "Slow on the Uptake," about a hooligan named Meier, and students either summarized the story or underlined passages where Meier differed from them.  A control group of 18 read a story with a protagonist who didn't do something stupid like go to a football match, get drunk, get into a fight and miss the actual game he attended.

Following reading the stories, students took a test on geography, science and the arts and it must have been hard because those who had read about Meier scored from 30%-32% but even the control group
and students who distanced themselves from the character by noting how he was different from them only scored 37%.   Still, a double digit percentage difference.   Was it permanent?  Let's hope not.  If hooligan stories make people dumber the entire country of Wales is doomed.

So read stories about Einstein, just not the ones where he forgets to put on his pants.

Citation: "A Story About a Stupid Person Can Make You Act Stupid (or Smart): Behavioral Assimilation (and Contrast) as Narrative Impact," Markus Appel, Media Psychology (April-June 2011)

Intelligence: Stupidity Is Contagious - Christopher Shea in the Wall Street Journal