It's interesting to analyze people not by how left-wing or right-wing they are, but instead by which direction their mistakes tend to be in. Which direction on the political spectrum should they have moved to make less mistakes?
I have found many of examples of mistakes in a leftward direction. Karl Popper was sympathetic to socialism and disliked the influence of TV. Friedrich Hayek supported a guaranteed minimum income. David Friedman incorrectly conceded points about public goods to anti-capitalists. Bryan Magee, Richard Dawkins, and William Godwin provide further examples. All of these people would be well served by more right-wing attitudes.
It's hard to find good thinkers who could be improved by being more left wing. The best example I've found so far is Ann Coulter.
In other words, here are some mistakes common to the left wing: environmentalism, anti-capitalism and socialism, authoritarianism, anti-Americanism, anti-semitism, cultural relativism, moral relativism, being a revolutionary. And here are some mistakes common to the right wing: homophobia, anti-semitism, being pro-life, creationism, being overly attached to religion over reason, sexism. The items on the first list of mistakes are considerably more common among good thinkers than the items on the second list.
What this means isn't obvious.