Right, Cookie -
As you know ROKA high command was staffed by Koreans who had served in the Japanese army. For example, Park Jung Hee, Chae Byong Duk, Baik Sung Yup, Kim Suk Won, Lee Ung Jung, Kim Baik Il and so on, were all graduates of the Japanese Military Academy or its branch in Manchuria.
Now, so what? Well, most of these men resented taking orders from their American advisors who they thought were less-trained in the art of war. Privately, they referred to the Americans as 'mi-guk-nom', where the suffix 'nom' denotes things bad (e.g., wai-nom for Japanese - "dwarfish SOBs", ddong-ddae-nom for Chinese - 'shit-filthy scums"...).
Capt. James Hausman, who was fluent in Korean, said that he was offended more than once by his Korean officers calling him "miguk-nom". Once he caught Park Jung Hee using the term.
BTW, there was an unreported incident that illustrates the point in case. During a meeting, a Korean major crashed in and pointed a pistol at Gen. Clark's head and threatened to shoot him. Fortunately, the major was wrestled down and led away. The major told his interrogators that he was angry at the Americans for "appeasing" the communists. Gen. Clark told the audience to keep this incident to themselves.
But this case was reported to Rhee Syngman and Rhee ordered the major released at once, saying that he wished that there were more patriots like the major in his army. Rhee believed that most of his generals worked for the Yanks and trusted only a few including Gen. Won Young Duk. Gen. Won orchestrated the release of anti-communist POWs. He also murdered a Rhee's opponent on Rhee's direct order (hand-written in English!), for which he was tried and imprisoned.
BTW, Chosun Ilbo wrote about this Clark incident last year.