This is an interesting thread...

But interestingly I've had zero problems with the CBSA. I have much more of a problem with the US agents. I've been flagged for secondary once, and hassled over my purpose for traveling to the U.S. Last time, I didn't have a business card on me (switched positions recently) and the agent gave me a long lecture that "the burden of proof is on me to enter the United States and if he is not convinced of my story he can refuse entry." Not sure if he was new or someone pissed in his Cheerios that morning or what, but he told me next time I had to bring a business card and that he was noting it on my file for the next time.

I'm back in the U.S. on Sunday so we'll see how that goes. I'll bring an old business card and I got an employment letter from work to explain all of the important questions.

Also, I notice sometimes US border agents stamp my passport with a B-1 Visa, and sometimes they just stamp my boarding pass with no visa (I'm a Canadian citizen).

It seems to me the US border agents are either one way or another - either I get waved through with barely a question (sometimes no questions(!)) or I'm interrogated. I'd much prefer this:

Agent: Where are you going?
Me: Indianapolis.

Agent: Why are you going to Indianapolis?
Me: Meetings at head office.

Agent: Who do you work for?
Me: A Canadian company.

Agent: Enjoy your trip.

What happens at a NEXUS interview?