Maybe a better example as a half decent defense attorney, or the judge, could get subsequent evidence thrown out there.

A cop pulls you over for a brake light. They decide to go fishing, asking where you're coming from or where you're going, looking for any inconsistency to pull on. Maybe they decide they smell something on your breath.

A well informed person would refuse to ask questions and help ensure the traffic stop can move forward with the ticket, the cop isn't allowed to hold you for longer than required for the initial offense.

Most people when asked questions, though, will answer. Most people asked to take a field sobriety test will oblige. None of that is required and all requires consent - the cop knows that and knows that few people will stand up for that.

Such fishing expeditions should be illegal and anything found should be considered inadmissible due to unreasonable search. When the professional trained in law knows that they can game the average person it should be unreasonable practice.