Even people meant to be caretakers can reflect society's imperfections; Miss Watson is one of those. She meant well, yes, but that doesn't mean her methods were exactly the most helpful. From her point of view Huck should be more civilized and she is constantly chastising Huck's seemingly inappropriate behavior. From Huck's perspective, it is rather unnecessary to correct his behavior because he never corrects anyone else's. It shows that Miss Watson is somewhat of a hypocrite. Going along with this as another example, she doesn't want Huck to smoke yet uses snuff herself.
Not to give any unwelcome praise to those unworthy, but the Duke and Dauphin played a rather substantial part in taking off Huck's hypothetical blindfold. To continue the metaphor, the Duke and Dauphin were the type of people that were indeed handed the 'short stick." For clarity purposes, the Duke and Dauphin were not a Duke or a Dauphin. They were only skilled in the art of deception and larceny, and yes, it is an art. Huck sees them as liars from the very beginning but only understands how cruel they really are through a series of deplorable events. It really all starts when the two first meet Huck and Jim and pretend to be poor woebegone forgotten royalty, and continues through swindling a poor religious group, putting on an incorrectly enunciated Shakespearian play, dressing up Jim as an "Arab," tricking a town full of people into paying for what was a scam of a show, and taking advantage of a hapless dead man. The last mentioned is by far the most cruel, and intentionally so. They pretended to be the deceased English brothers in order to obtain his will money, one of them doing the impertinent deed of faking deafness. Though Jim is oblivious, Huck understands that what the men are doing is horridly disdainful and cruel; he only stays with them in fear that they would turn either Jim or him in.