and thinks she is pretty. He states this twice. This worries George, who knows how easy it is for Lennie to get himself into trouble. Overall, George is concerned because a young, pretty, and provocative young wife of a hot-headed ranch owner's son spells danger to him. George especially wants Lennie to avoid her. He takes Lennie by the ear, shakes him, and says:

“Listen to me, you crazy bastard,” he said fiercely. “Don’t you even take a look at that bitch. I don’t care what she says and what she does. I seen ‘em poison before, but I never seen no piece of jail bait worse than her. You leave her be.”

This scares Lennie, who is intuitive and suddenly has a premonition of disaster. He tells George that the ranch isn't a good place and that he wants to leave.

I think that George sees Curley's wife as a form of "bad news."  This idea of how bad she can be is enhanced by the "vamp" ways in which she carries herself and the reputation she has developed among the other farm hands.  George also sees Candy as triggering something else in terms of his relationship with Lennie.  The incident that Lennie had back in Weed was the reason that both he and George had to live on the run from there.  George is wise enough to understand that a similar situation could result itself with Curley's wife.  The significance of how George sees Curley's wife is large because George understands that Curley's wife could present herself as an obstacles to the men's happiness and achievement of their dreams of their own farm.  George's view of Curley's wife is something that he wants Lennie to understand in terms of "staying away from her" because she is seen as "bad news."  In tihs, George looks out for Lennie, and protects him from harm, a danger that he knows all too well because of how he knows Lennie and what he knows about his past.  It is here where the significance of how George sees Curley's wife is present.

On the most surface level, Lennie sees Curley's wife sees her as "purty."  Lennie is entranced with her beauty.  Steinbeck enhances this with his description of her as how Lennie sees her in the moment where they are together.  The "tight sausage curls" as well as her made up face are examples of how Lennie sees her as something "purty."  Something noticeable is that Lennie is entranced by her beauty, and wishes to hold it in his own hands.  It is here where a theme seems to re-emerge in terms of how Lennie's own embrace of beauty ends up killing it.  This is seen in how he treats the animals, lovingly and caring, but still it is one of death. It is also representative of what happened in Weed, when he came too close to a girl only to scare her and be run off with George.  In this light, the significance of how Lennie sees Curley's wife is that it is a continuation of this pattern.  When Lennie goes to touch her hair, he does so with such a tender embrace that ends up being so destructive in his big hands that the slippery slope quickly moves from Lennie's embrace of beauty and his penchant for killing it.  In this, the significance of how Lennie sees Curley's wife is another way to heighten how, while Lennie has no malevolent intent, he is incapable of appreciating beauty in his own destructive hands.