There is so much to be said about this play. For one thing, it constitutes a satire, because it criticizes common polite society through the lens of irony and vice. Also, it constitutes a comedy in form (in the Aristotlean sense) because it ends with a marriage, and even a funny marriage at that: The marriage of the town whore to the town thief. This union of monetary greed constitutes an archetypal event, the marriage of the beast and the harlot. Ultimately, then, the story is about the vices of lust, greed, and hedonism, and the always timely judgment of the wicked.
The sin of the prostitute is complex, because in her case, it was her own mother's betrayal that left her morally and emotionally corrupted, because it was her own mother who submitted her to that lifestyle, although the implication is clearly that she later adopted the identity for herself and became a willing participant in the prostitution. More importantly, though, the prostitute represents the entire village community, because she knows secrets about everyone in town. Humorously, when the Courtesan plays sick, Sir Bounteous himself of all people decides to pay a visit and he comments that she's probably pregnant with his baby. It seems not even the patriarch of the family is above prostitution. Therefore, the prostitute character does not really represent female vice, but rather, she represents the lust of all people.
Likewise, the robber does not steal from a stranger, but from his very own inheritance. This is a cosmic symbol of those who behave selfishly in a world with so much to offer at such little cost. Look at all the trouble the robber goes through just to succeed in petty crimes. And again, everything he takes is from his own inheritance. Therefore he also does not represent himself, but the selfishness of all people. His greed for wealth leaves him emotionally compromised, but most of all, it makes him unwise.
So unwise in fact, that even though every other person in town knows that the Courtesan is a lifelong prostitute, the thief never even realizes it and he takes her for his wife. This is the play's way of suggesting that maybe everything works out correctly in the long run, and perhaps, as Brothel learns from the succubus, perhaps human evil is rewarded with divine punishment.
