"Shall I expound whore to you?": Metaphorical Graspings at a Definition

During the "Arraignment of Vittoria" (III.ii), Monticelso spends twenty three lines defining "whore." In terms of length and language, this "definition" is very similar to Hippolito's misogynist rant to Bellafront in "The Honest Whore." In both cases, the male speakers use a host of metaphors and similes in an attempt not only to make Vittoria or Bellafront feel guilty for her actions, but also to provide some sort of working definition of "whore." Why do these characters spend so much time trying to define this word/"vocation"? What does their reliance on metaphor say about the nature of their positions? Why is it important that "whore" is difficult to define at all?