Giorgio Bassani published a collection of short stories with the deceptively innocuous title The Smell of Hay. I suspect that for many people, that triggers fond, nostalgic associations with spring and summertime–universal and perennial symbols of new life, new hope, and the prime of life. Likewise, I'm sure that for many people, summer represents the carefree days of youth. Some of their fondest childhood memories are memories of summer break. The mere sound of lawnmowers can instantly evoke that past.
In that respect, Bassani's title is subversive, because the default associations are juxtaposed against the intended meaning. The title fosters a false impression that Bassani will sabotage. In the context of the stories, the smell of hay alludes to mown hay at the gates of the 17C Jewish cemetery in Ferrara. In context, it has reference, not to hope and halcyon youth, but to death and forgetfulness. Bassani trades on the contrast between the default association and the abrasive context.
And it has a more sinister significance. Not death by natural causes, not death from old age, but the Holocaust. Of the 760 Jews who lived in prewar Ferrara, only 200 survived. So many of Bassani's Jewish friends, neighbors, and classmates perished in the gas chambers. So his title is actually ominous.
Bassani wrote to keep their memory alive. Ironically, he is now interred in the very cemetery his title evokes.
At one level, this illustrates the open-textured character of metaphors. Metaphors have surplus meaning. What they signify is context-dependent.
But to some degree it illustrates the ambiguity of good and evil. I don't mean to suggest that good and evil are generally ambiguous. There are unambiguous examples of good and evil.
However, there are situations in which one person's good is another person's evil. What is beneficial for one person may be maleficial for another. For some people, the fragrance of fresh-cut grass brings back memories of a happy childhood. But for Bassani, it's the stench of death and moral horror.
That complicates the problem of evil. For there are situations in which good and evil are relative. That's not to deny absolute good and evil, but not every event can be dichotomized in that fashion.