Even in her most uneasy moments—even when she had been agitated by Mrs. Cadwallader’s painfully graphic report of gossip—her effort, nay, her strongest impulsive prompting, had been towards the vindication of Will from any sullying surmises; and when, in her meeting with him afterwards, she had at first interpreted his words as a probable allusion to a feeling towards Mrs. Lydgate which he was determined to cut himself off from indulging, she had had a quick, sad, excusing vision of…
…the association with this man had been fatal to him—true that if he had had the thousand pounds still in his hands with all his debts unpaid he would have returned the money to Bulstrode, and taken beggary rather than the rescue which had been sullied with the suspicion of a bribe (for, remember, he was one of the proudest among the sons of men)—nevertheless, he would not turn away from this crushed fellow-mortal whose aid he had used, and make a pitiful effort to get acquittal for…
There are no more uses of "sully" in the book.
Show samples from other sources
And though in near time we did sleep together (with a genuinely pleasing, if sober, conviviality), I came to think of that first interlude with a somewhat sorrowful fondness, for I saw that our days together were perhaps sullied from the very beginning and all the way through, right up to the last.
Chang-rae Lee -- A Gesture Life
Maybe I would waste my time on skills I didn’t care about—like sword fighting or badminton—but I would not sully the memory of my once-perfect music and archery.