Actually Clarkson likes America just fine. Last Christmas he was posting photos on twitter of his vacation at a Florida resort where he was shooting skeet from the roof of the hotel. He said it was one of the great things about America.
In his interview with Jay Leno he says he used to come to America and it felt like a prison and going home was returning to a free country. Now he feels like its the other way around.
Jay Leno Interview and Lap - Top Gear - BBC