You're too easy - only a current or retired cop would answer the question that way.If the officer asks if I know why he stopped me, I will answer, with a smile, "I bet your gonna tell me".
Now that being said, whenever I do stop someone it's for a legitimate violation. As you're well aware, with our Transportation Code there is no way a person can drive around town for more than 2 minutes without violating several sections of it - PC should never be a problem for a traffic stop in this state
Now when I do have someone stopped on traffic I like to talk them. I guess it's just my nature to be friendly and most people are all uptight about being stopped anyway so maybe it will put them at ease.
Also, if my gut says to look a little closer to see what I might find - "a fishing trip" as you refer to it, I will ask them a few questions. You'd be surprised (well, you wouldn't be but most people would be) at what people will tell you when you just ask them questions like, "Are there any drugs in the car, weapons, guns, knives? Do you have any warrants out for you arrests? Does this car belong to you?"
Unless one is a real sociopath (like Ted Bundy) it gets fairly easy to read people. Hence my comment to txinvestigator about his reply - the average citizen would never make a statement like that. I don't write very many tickets (we've got plenty of officers on our department where traffic enforcement is their primary responsibility) but I will stop people and let them know what they're doing that is in violation of the law so that maybe they will change their behavior. However. blow through a red light, speed through a school zone, or have babies in the vehicle with no car seat, and you're probably going to get a ticket from me.
Head txi's advice and be truthful with any LEO that asks you questions. Don't lie or play games - if you're caught (most of the time you will be) you probably won't like the outcome. CHL holders are as a group very much law abiding citizens and as such rarely come into contact with LE. The ones that I've met on traffic stops have always been easy to deal with.