OP - please, just answer the questions. Don't be goaded into getting your back up at a border crossing. Save that for something important such as when your morning paper isn't delivered.
My wife and I cross most of the time at the sleepy Chief Mountain crossing in Montana during summer vacations. We have been asked if we carried $10,000 or more in currency, if we had firearms, cigarettes or alcohol and if we possessed bear spray (which you cannot bring into Canada). Sometimes we are asked about fruit. Once we were asked by a good humored agent if we were eloping. We answer all questions. Before beginning each trip we always look in the trunk of our rental car before making our first border crossing. We have never had a problem going north or south.