One topic that often comes up in serious conversations about 2016 presidential politics is whether questions about Hillary Clinton's trustworthiness will be her undoing. Not surprisingly, many of her fiercest critics passionately want this to be the case, but even some of her closest advisers are known to be very concerned about it. It was enough of a worry for Clinton to insist in a recent interview with CNN's Brianna Keilar, "People should and do trust me." Will it be a deal breaker for her candidacy? Those of us who think about politics a lot frequently make the mistake of seizing on one factor and deciding that it is all-important, to the exclusion of any other questions or issues, including ones that might work in an opposite direction. This is well and good so long as you obsess on the factor that proves to be decisive, but there is a danger that you could focus on the wrong one, or one that is important—just not all-important. A good example of this can be found in the 2012 presidential exit polls.

More from the Cook Political Report