Could you be more specific?
I don’t want to cite the particulars because discussions of grammar and the like on FR turn into their own rancorous (and largely erroneous) threads.
But the head of the copyediting department at a VERY prestigious house was so annoyed with the mistakes he made that she sent him a letter about them, and he refused to change his “rules.”
As for the quality of his books, in his genre they were the best. Imitators just couldn’t cut it. The timing of the horror was exquisite—it’s a talent in its own right. They were usually huge mothers, and difficult to work on, especially after you had read them through once and knew the story.
In contract, Saul Bellow loved the work of his copyeditor so much that he had it written into his contract that she must always be the copyeditor on his books. He gave her gifts.
At one point Harper & Row had Webster’s 11th Unabridged written into their contracts to try to avoid the endless disputes on spelling that self-important authors would get into with the copyediting department. Of course the boilerplate was negotiable for each book contract, so some got away with deleting that sentence from the contract.