yes, many KMT officials were corrupt ( probably over exaggerated as well )
ROC economy collapse after 1947 was not due to the massive KMT corruptions ( Communists records ) but the scheming and sabotage works of Communist Harry Dexter White and Cronies in U.S. Treasury department and CCP spy Ji Chaoding in China Finance Ministry. The 8 years Sino-Japanese war ruined China economy, Ji Chaoding deliberate awful advice on KMT disastrous monetary policy caused massive inflation and China economy inevitably collapsed. More KMT troops started defecting to CCP when the central govt cannot pay or feed them. Peasants start to rebel against the central govt. ROC economic collapse ( CCP sabotage ) was the catalyst for social disruption and peasants switching support to CCP.
like I said earlier, it was not the mandate of Heaven that chose CCP nor their military superiority that won them China. Soviet Russia with British and American help gave birth to People Republic of China. The Western Powers China Containment Policy was the destruction of Republic of China.
Roosevelt and Truman official policy for China from 1941 were to preserve the territory and administrative integrity of the Republic of China and to support Chiang Kai Shek as leader of central govt of China. Why did USA eventually abandoned ROC to face her defeat alone in 1949 to the disbelief of the free world who were fearing Red China and Soviet Union alliance.
Truman was misled or deceived by the American communists or pro Soviet elements ( Marshall, Acheson, Hopkins, Lattimore etc... ) who had infiltrated his govt, taken over control of American state of department thus directed USA failed policy toward ROC. The Russians and CCP knew in no doubt that ROC was heavily depleted, on the verge of collapse after WW2. ( politically, financially, militarily and spiritually ) If they can stop American assistance to ROC militarily and financially, Chinese Nationalists will be defeated.
read somewhere ( unconfirmed ) that after the last batch of VENONA Papers, Russian and FBI declassified files in the early 1990s, Joseph McCarthy got a high 90% of the Russian Communist agents in American govt correct. The peoples of Wisconsin were apparently campaigning to restore Senator McCarthy good name.