First Mao was not a good governor, but a great revolutionist. It is Peter's Principle.
China did express its gratitude to the USA, especially the Flying Tigers. There were some US veterans honored by the president in China - just watched CCTV-News in English. Unfortunately most have passed away by now.
On a personal note. About 20 or so years ago, I was bummed out of the best hotel (at the time) in Taipei due to the greeting of the Flying Tigers. I was furious but now I thank for what they did and they had more right to stay in that hotel than I.