It really depends on the context.
Some are really smug, self-righteous blowhards more interested in talking than listening, and the best you can do is poke fun at them to amuse an audience.
Some are really willing to discuss things openly; they often ask a lot of questions, so you need to know yourself to do this.
Some just put up a brick wall and tune you out entirely; these are the most infuriating. No matter what you say, it glances off like water off a duck's back. If you get in a conversation with one of these, don't waste your time, you'll only frustrate yourself.