The Duke and the Dauphin are both comic characters whose flamboyance and false airs provide much in the way of amusement. Yet at the same time, they're a couple of amoral grifters who'd merrily sell their own grandmothers if the money was right. Although their exploits may be amusing, we're also aware that we're dealing with a couple of serial crooks who routinely con the weak and vulnerable. This adds more than a touch of darkness to their scams.
The Wilks ladies are especially vulnerable on account of their recent loss. They want to believe, for their late father's sake, that the two men who arrive at their house really are their uncles William and Henry. When the Duke and the Dauphin are ripping off greedy suckers, then it's not quite so bad, though still morally and legally unacceptable. But when their latest marks turn out to be sweet, naive, trusting young ladies who've recently suffered a bereavement, then we can only acknowledge the dark void where their souls should be.
Nevertheless, considerable amusement is still to be found in the Wilks episode. Huck gets trapped in a lie, pretending that he attends the same church as the King of England. But as Joanna points out, the king lives in London, whereas Huck claims to live in Sheffield, a city in northern England 142 miles away from the capital. Huck pretends to choke on a chicken bone to give him time to think of a way out of his predicament. But he just keeps on digging himself deeper into trouble, saying that the king regularly stays in Sheffield during the summer to bathe in the sea. Sheffield, however, is landlocked, quite some distance from the coast.