| Quote #1
MRS. CHEVELEY. I have a distinct recollection of Lady Chiltern always getting the good conduct prize! (1.66)
Mrs. Cheveley thinks that ethics are just obedience.
| Quote #2
MRS. CHEVELEY. [In her most nonchalant manner.] My dear Sir Robert, you are a man of the world, and you have your price, I suppose. (1.252)
Mrs. Cheveley is saying that a man of the world recognizes that principles bow before needs (i.e., he'll do what it takes to get what he wants politically). Sir Robert has accepted that law before, and Mrs. Cheveley expects he'll do so again. Like Lady Chiltern, she doesn't believe people change.
| Quote #3
LADY MARKBY. Lady Chiltern is a woman of the very highest principles, I am glad to say. I am a little too old now, myself, to trouble about setting a good example, but I always admire people who do. (1.290)
It's funny how Lady Markby equates holding the highest principles with setting a good example. For her, if a tree falls in the forest and no one can hear it, it doesn't make a sound. In other words, morals only matter if other people can see you upholding them.