Thanks to Jason, I learned of some weird but unsurprising research that brings together the bad apple studies described in Good Boss, Bad Boss and work on emotional contagion in The No Asshole Rule. A five-year study led by Mississippi State University Associate Professor Rhonda Vann found that cows that were "very aggressive, excitable, and out of control" not only got sick more often, weighed less, and wrecked farm equipment, these bad things "rub-off" on the rest of the herd. Here is the story from Delta Farm Press, called "Calm Cattle More Valuable." Of course, human groups are different from farm animals in many ways, but the parallel between this and Will Felps' research on bad apples, and related work on "bad is stronger than good" is striking (See this HBR post).