There is a remote border crossing between Edmundston, New Brunswick and Madawaska Maine that I used to make several crossings a year for business. Crossing into Maine I was searched several times. In fact, I would say that I was searched over 50% of the time. I made three or four trips a year to this location and I would make several crossing each trip. My car was searched while I went inside to sit in a lobby. I wasn't allowed to use the restroom until they were finished searching my car. I wasn't anywhere near my car at the time that they were searching so this made no sense to me. One time they found a dozen hats with my companies logo on it and the border agent thought she hit the jackpot. She told me about the textile tariff on goods imported into the USA from Canada. I told her that I had brought them from the USA anyway and they were cheap hats and she could keep them. She eventually let me go. Finally, when I was turning my territory over to another representative, I was stopped for the umpteenth time. Finally, I asked the officer "Why are you always stopping me?" She told me that it was a local crossing and they know most of the people that cross the border with frequency. I'm just an unfamiliar face so that is probably why they stop me.
Later, my customer (who is also my friend) laughed at my story and told me that an American crossing into the USA diving a car with a Quebec plate is probably an unusual occurrence at this border crossing. Living at the border all his life, my customer related his experience with a particular crossing guard that harassed him every time he crossed that border over a ~30 year period until the officer retired. It was like a school master quizzing an adolescent. There was no purpose other than the power that the agent wielded over my friend who needed the agents approval to cross the border.
I once was in CT for a conference and I decided to leave the conference early so I could drive up to Montreal for an overnight trip and see a GoodGirl. It is unusual that I am within reasonable driving distance so I decided to take advantage and burn some hotel points. Upon driving back to the USA, the border guard asked me what the reason was for my trip. I told him I decided to drive up for dinner and drinks. The agent became real excited and said "You expect me to believe that you drove all the way up to Montreal to have dinner and a few drinks?" I calmly gave him a one word answer "Yes." Then he repeated himself and I said "Well, that and hit a few clubs." He was happy with this answer and his attitude changed as soon as heard the word "clubs." Apparently, going to a few clubs is plausible for an overnight trip. He said "OK, pop the trunk" and within 30 seconds I was on my way.
I honestly do not know if it is easier to claim business or pleasure when crossing the border. Once, when driving through upstate New York I said my reason was business. The twit of a female agent wanted the address of the company and contact information of the people I was calling on in Montreal and a letter of invitation. I couldn't produce a letter of invitation but I had contact information and correspondence with the client by e-mail that I could show her on my BlackBerry. So far so good I thought and then the twit starts asking me "What are you going to say in your meeting? Like how do you sell your product? Like what are you gonna say?" This was really bizarre and I looked at her with a puzzled and said "I have a PowerPoint presentation." She went on with more silly questions about my presentation. It was a bizarre line of questioning. finally, she asked me to go inside where I spent 45 minutes waiting while a guard took my laptop and Black Berry into another room. They eventually let me go but I was held up an hour or so. I recanted my story to the manager at the Omni, Mount Royal. She said that I should tell them I'm going over for pleasure to have dinner etc.
I still think that if you are on a short trip, the best thing to say is that you are going over to hit a few clubs and to try your hand at the casino. They will infer that you mean gentlemen's clubs and let you go.