After stradlater asks holden to write his essay, holden says, "[stradlater] wanted you to think that the only reason he was lousy at writing compositions was because he stuck all the commas in the wrong place." then holden says about an experience with ackley at a basketball game, "ackley kept saying . . that coyle had a perfect build for basketball. god, how i hate that stuff.
" why does holden hate this "stuff"?
how does this relate to holden’s disgust with phoniness?

Holden hates people's ever-showing phoniness.

Explanation:

By this chapter in the novel, you can already identify most of the phony details that make Holden tick in irritation. One of these many details is the various compliments and unnecessary comments that appear throughout the novel. This is one of those.

Why does Ackley need to state it in such a "corny" way?

Or take Stradlater, as another example. Whenever he needs to ask for somebody to do him a favor, just like in this situation where he's asking Holden to write his composition for him, he feels the need to utilize compliments such as "hot-shot" or friendly nicknames like "buddyroo".