According to the Times,
Bush doesn't understand why so many Iraqis hate the U.S.
More generally, the participants said, the president expressed frustration that Iraqis had not come to appreciate the sacrifices the United States had made in Iraq, and was puzzled as to how a recent anti-American rally in support of Hezbollah in Baghdad could draw such a large crowd. “I do think he was frustrated about why 10,000 Shiites would go into the streets and demonstrate against the United States,” said another person who attended.
Maybe he should invite Jon Stewart over to explain it to him. Or perhaps read an analysis in a newspaper or a few articles or a book or something?