I've crossed into Canada numerous times. On the Buffalo border, if you basically said "I'm going to the casino" or "I'm going to the strip clubs", they just waived you right in.
On the way back, depending on the person at the booth, it could either be a stern questioning, or a waive through. You learned to guess the demeanor of the agents by looking at the lines of cars; if one line was moving very slowly, it was best avoided. As a general rule of thumb, the less you say, the better (of course, it shouldn't be _obvious_ that you're biting your tongue and withholding information; just be polite, courteous and to-the-point).
On the way back, depending on the person at the booth, it could either be a stern questioning, or a waive through. You learned to guess the demeanor of the agents by looking at the lines of cars; if one line was moving very slowly, it was best avoided. As a general rule of thumb, the less you say, the better (of course, it shouldn't be _obvious_ that you're biting your tongue and withholding information; just be polite, courteous and to-the-point).