How does Wilde use the play The Importance of Being Earnest to satirize the heroic morality of the upper classes?

Oscar Wilde was an avid satirist of what he viewed as the pretensions of upper-class Victorian society. His play The Importance of Being Earnest is not directly about the foibles of that society. Rather, it is about the subterfuge in which the play’s two main protagonists, Jack Worthing and Algernon Moncrieff, engage as a means of cutting loose and avoiding responsibility respectively. While the play is centered upon the difficulties that arise when worlds collide and deceptions become increasingly inconvenient to perpetuate, the setting provides for ample opportunities for Wilde to skewer Victorian social customs, particularly in the persons of Lady Bracknell and Miss Prism.
Much of The Importance of Being Earnest takes place at Manor House, a palatial estate in Hertfordshire, in addition to the opening scenes at Algernon’s London apartment, described in the play’s directions as “luxuriously and artistically furnished.” An early clue as to the upper-class pretensions of Lady Bracknell is offered in the opening dialogue between Algernon and his manservant, Lane, in which the former, anticipating Lady Bracknell’s arrival, asks Lane, “have you got the cucumber sandwiches cut for Lady Bracknell?” Cucumber sandwiches were associated with the upper class and Lady Bracknell’s preference for such an item is intended to convey the sense of snobbishness that Wilde sought to invoke.
Lady Bracknell’s entrance into Algernon’s apartment introduces the audience to the character and her myriad foibles and pretensions. As the play progresses, examples of Wilde’s efforts at satirizing Victorian social customs continue. In responding to her nephew’s statement that he will miss dining with her because he must attend to Bunbury (a nonexistent person Algernon uses to evade unpleasant situations), whose health, he declares, is in decline, Lady Bracknell states,

Well, I must say, Algernon, that I think it is high time that Mr. Bunbury made up his mind whether he was going to live or to die.  This shilly-shallying with the question is absurd.  Nor do I in any way approve of the modern sympathy with invalids.

This cavalier attitude on the part of the wealthy Lady Bracknell toward the lower classes constitutes the playwright’s most scathing commentary on Victorian society. As Lady Bracknell interrogates Jack regarding his suitability to court Gwendolyn, she informs him,

I feel bound to tell you that you are not down on my list of eligible young men, although I have the same list as the dear Duchess of Bolton has.  We work together, in fact.  However, I am quite ready to enter your name, should your answers be what a really affectionate mother requires.

As she continues to question Jack regarding his background, the Lady again injects a certain invective into her views of others:

Lady Bracknell:  [Sternly.]  What are your politics?
Jack: Well, I am afraid I really have none.  I am a Liberal Unionist.
Lady Bracknell:  Oh, they count as Tories.  They dine with us.  Or come in the evening, at any rate.  Now to minor matters.  Are your parents living?
Jack: I have lost both my parents.
Lady Bracknell:  To lose one parent, Mr. Worthing, may be regarded as a misfortune; to lose both looks like carelessness.  Who was your father?  He was evidently a man of some wealth.  Was he born in what the Radical papers call the purple of commerce, or did he rise from the ranks of the aristocracy?

The Importance of Being Earnest is replete with examples of Wilde’s interest in satirizing the morality of the society in which his play takes place. By providing such a prominent place in his play for his most pretentious character (Lady Bracknell), it is made exceedingly evident that Wilde intended for this component of his work to be just as important as the underlying plot regarding Jack’s double life, his romantic intentions toward Gwendolyn, and the revelations regarding Jack and Algernon’s relationship, among other plot points.