In chapter 30 of "The Adventures of Huckleberry Finn," what admissions are made by the duke and king that prove they are not purely villainous?

After Huck admits the truth to Mary Jane in Chapter 29 of "The Adventures of Huckleberry Finn" that the king and duke are imposters posing to rob the Wilks family of their inheritance, there also comes the moment of truth for the duke and the king in Chapter 30.  When the king attacks Huck for "tryin' to give us the slip," the duke comes to his defense, identifying with Huck as one fleeing from a mob,

'Leggo the boy, you old idiot!  Would you a done any different?  Did you inquire around for him, when you got loose?  I don't remember it.'

Subsequently, they argue about who has hidden the money in the coffin,the duke admits that he had thought of taking the money and giving everyone the "slip," the king, too, confesses that he was also so motivated, "'Nought!--I own up!"

Thus, for the first time, the king and the duke display some honesty, disproving the old adage that "There is no honor among thieves."  However, after they retreat to take comfort from "their bottles," another adage does prove true.  For Huck narrates that "they was as thick as thieves" again.