Herodias takes a lot of flak in Salomé. Jokanaan just keeps insulting her.
And, to be fair, she kind of deserves it. She's guilty of adultery and incest, after all: those are pretty big no-nos. In the end, though, it's not just Jokanaan's insults that matter, it's Herodias' reaction to them.
Sure, she has Jokanaan jailed for his comments—or so it says in the Bible; it's never stated specifically in the play—but Herodias seems to be little more than annoyed by Jokanaan's ranting and raving. Jokanaan is aware of this.
Herodias never betrays a hint of remorse. In fact, even though she doesn't tell Salomé what to ask for—in the Biblical accounts she tells her daughter to ask for dude's head—she's totally filled with joy at the prospect of seeing Jokanaan's head on a silver platter.
Even after Salomé has begun talking to the beheaded Jokanaan, even after Herod has turned away, horrified, Herodias remains supportive:
"I am well pleased with my daughter. She has done well. And I will stay here now." (375)
Um. That's sick. Remember that Salome is addled by crazy lust…Herodias is just out for revenge. The fact that it's cold-blooded makes it way worse. And all Herod can say in reply is, "Ah! There speaks my brother's wife!" (376).
Yeah, even though Herodias might be tired of Jokanaan's insults, she embraces her reputation as "my brother's wife:" as an adulterer, a debased woman. She is immoral, plain and simple, unconcerned with sin and bad omens, secure in her own behavior, regardless of what her critics might say.