Good advice. I experienced the same thing when coming into Canada recently as a non-Canadian. The agent asked me if I had been to Canada before and I said know.
He then found a stamp on my passport (which was only there because I got a connecting flight to Chicago from Toronto - I never left the airport) I got another round of questions and even further questioning by a second immigration officer.
Granted, I am staying for almost the maximum time allowed without a visa (6 months) but such a minor slip-up can lead to a lot of extra questions and if you slip-up on them you could be on your way home. It's always good to know what you are going to say before you reach the desk, at least as much as possible.
I spent about 3 hours in Canada Immigration on my first trip to Canada, I now live here. IMO Toronto Pearson's border control are the worst I've ever experienced.
I made the honest mistake of being honest. I was working as an electrician for my fathers company, which meant I had a plenty of money and as much holiday time as I wanted (I declared I was taking 2 weeks, and the officer acted like this was a lot).
My second mistake was being nervous. I came from the UK where our police, even at the border, are professional, courteous and aren't carrying handguns. The Canadian border officer was extremely rude (In dealing with 5 female officers and 4 male officers I found the male ones are the only professional and courteous officers employed by CBP).
After being questioned for an hour I was taken to get my bags searched. The male officer doing the searching was extremely polite and professional. He opened my suitcase (for a very messy person, my luggage is always meticulously packed to maximize space) and automatically adopted "We're not going to find anything here" mode, like you visibly saw the guy relax and he started chatting about the books I'd brought with me (one was a manga that he bought his kid).
I then got questioned further, and taken back to the immigration desk and asked to wait. This is when I overheard another male officer say "He's got nothing, you should have known that in the first five minutes. Just let him go." So she asked for the contact information, accused me of them being false when they didn't immediately answer (noisy terminal and 2 hours waiting). I asked if I could text them, and got grilled for her accusing me of keeping my phone on. I basically threw my phone over the desk at her and said "No it's been turned off for the past ten hours!" Then her attitude changed.
Since then I've rehearsed everything I've said. Act pissed off and say as little as possible. When I get to the person who checks my claims I say, sounding extremely pissed off "Hey, how are you?" I take the same policy whenever I get sent to the actual officers (it happens way to frequently, I have no clue why, apparently being completely white bread I look like a major terrorist threat - actually with my knowledge of chemistry and physics I'm probably a bigger risk than any of the guys who hijacked the planes on 9/11 as I actually know how to make a nuclear bomb - probably a very, very dirty bomb - and explosives).
I was detained for several hours at the Montreal airport trying to enter Canada. The immigration officer at one point started yelling at me about Wal-Mart and how Canada isn't like Wal-Mart and the workers in Canada have rights! None of which had anything to do with me. I assume she was having a bad day and decided to take it out on the first American she came across.
She began insisting that I pay $1000 cash to enter the country with my laptop and printer. I refused to give her cash but offered to pay with a credit card. That got me detained for another hour, sitting alone locked in a room.
Finally she brought someone else out that wasn't irrationally mad at me and she charged my credit card $250. The entire thing was surreal.
He then found a stamp on my passport (which was only there because I got a connecting flight to Chicago from Toronto - I never left the airport) I got another round of questions and even further questioning by a second immigration officer.
Granted, I am staying for almost the maximum time allowed without a visa (6 months) but such a minor slip-up can lead to a lot of extra questions and if you slip-up on them you could be on your way home. It's always good to know what you are going to say before you reach the desk, at least as much as possible.