He tells some of the tricks he uses. He is permitted to lie to you. Talk to him, and you are screwed - even if you are as pure as driven snow (which nobody is).
One great line: "If I follow you in my car long enough, eventually you will do something to give me legitimate reason to pull you over." Another: "Let's talk off the record." (There is no such thing as "off the record.")
I am convinced. The correct response to cops of all sorts is "With all respect, I wish to consult with an attorney."