In Shakespeare's Hamlet, Hamlet seems to be an excellent judge of character, and he finds Polonius wanting of any.
He is flippant and sarcastic and insulting when dealing with Polonius. He is also grotesque with his imagery when talking to or about Polonius.
For instance, in Act 2.2 Hamlet enters the stage reading a book. Polonius quickly urges Claudius and Gertrude off the stage so that he can "board" Hamlet, approach him and determine if his theory of why Hamlet is mad is accurate.
Repeatedly in the work, others think they can "play" Hamlet, so to speak. They think they can talk to him and manipulate him and determine his motivations, etc. Polonius tries this here.
Hamlet plays Polonius instead, figuratively disarming him with his opening remark:
...you are a fishmonger. (Act 2.2.173)
When Polonius denies this, Hamlet answers that then he wishes Polonius were as honest man, for honest men are as one in 10,000 in the world. This seems to be an indication that Hamlet knows Polonius is, in a sense, spying on him, and seems to be a verbal slam against Polonius for attempting to do so.
Hamlet then changes the subject again, twice in one sentence, actually, while, apparently, reading from the book he is carrying:
For if the sun breed maggots in a dead dog, being a god kissing carrion--Have you a daughter? (Act 2.2.180-181)
This is an allusion, I believe, to the scientific observation and mistaken belief that maggots could spring to life out of the carcasses of dead things. The grotesque imagery is intended as a reflection on Polonius, of course.
Hamlet then proceeds to insult Polonius's daughter, supposedly summarize nasty things the book he is reading says about old men (which Polonius is), and tell Polonius, when Polonius says he will take his leave from Hamlet, that there is nothing Hamlet would rather part with.
In short, Hamlet's behavior toward Polonius is insulting and provocative. And what Hamlet thinks of Polonius can be seen in numerous instances in the play, but perhaps no where better than where he tells Claudius the location of Polonius's body:
Not where he eats, but where a' is eaten. A certain convocation of politic worms ar e'en at him. (Act 4.3.19,20)