For working so hard to come up with nice things to say. Clinton liked the exhibits, Carter thanked Bush for helping (meekly) Africa, Obama said Dubya was a nice guy. The 600 pound elephant being that Shrub almost destroyed the country. Nobody really had to say it, everyone but the nitwits knows it.
The thing to remember about Bush's presidency is it was not just his incompetence that brought the country down it was just as much because he followed conservative policies like letting the free markets run wild. And they did. Then housing collaspded, Wall Street collasped, credit collasped, jobs collasped.