Delicious bits of irony in The Beggar's Opera

The Beggar's Opera turns London upside-down, not only displaying the city's writhing underbelly but nearly glamourizing it. I'm particularly enjoying the little bits of irony found in many places. Various crimes are given degrees of value: "Murder is as fashionable a crime as a man can be guilty of" (I.iv 33) said Peachum, whose very name takes a slimy connotation bearing resemblance to the term "peached" meaning to inform against someone.  This tongue-in-cheek exaltation of crime is why Mrs. Peachum is fast becoming my favorite character in the play.  She wants her daughter Polly to essentially be a whore, as wives are poorly treated and mistresses treated favorably.  She is upset when Polly announces her marriage to the highwayman Macheath.  "Why must our Polly, forsooth, differ from her sex, and love only her husband?" (I.v 2)

Mrs. Peachum says many things about love and marriage which contradict conventional morality:
"Tis marriage...that makes it a blemish" (I.ix 6),  "The comfortable state of widowhood is the only hope that keeps up a wife's spirits" (I.x 22), and when suggesting Polly inform on Macheath to have him hung she says "what many a wife would give for such an opportunity" (I.x 48)

She also utters the heavily ironic line "hang your husband, and be dutiful" (I.x 67)  This line reminds me of the satirical opera Pirates of Penzance, where characters do ridiculous and impractical things because they are bound by a sense of duty. This particular duty Mrs. Peachum mentions is surprisingly dark.

Finally, Mrs. Peachum speaks a line which is supremely ironic: "Those cursed playbooks she reads have been her ruin" (I.x 62)  Upon reading some data concerning the critical response to The Beggar's Opera, I found some writings which were concerned that the populace of London would emulate the characters in the play.  It seems John Gay foresaw this when he baked this delicious line in the text.  This is satire at it's finest: having  dubious sentiments spoken as truth by characters who are essentially idiots.  This is a very subtle way of suggesting that people who are concerned with the moral messages of the play are idiots.