For a perspective from the other side of the border (I'm from the US): I've been to Canada a few times as a tourist and on business over the past decade, never staying more than a few days. Every time, without exception, I've been on the receiving end of "aggressive", extended questioning, ranging from such oddities as "You're here for our free health care, aren't you? Admit it! Just tell us you don't have insurance!" to lines of questioning that suggest involvement with a drug cartel.
I've also been subjected to extensive physical searches of all my belongings. (And just to be clear, I'm a healthy, Caucasian, 20-something, US born-and-raised, male.)
I often think of most Canadians as being friendlier than a lot of people around the US, but immigration and border control aren't one of those areas.
I had the same experience... I visited Montreal last month for a business trip, first time in a couple of years, and had 40 minutes of rather hostile questioning on my way in.
It didn't make much sense to me, and I assumed that they'd picked a middle-aged, grey-haired, white guy so that they couldn't be accused of racial profiling... but from comments here it seems it is a lot more general.
Some of the questions didn't make a lot of sense (especially not at gone midnight), one or two were personally rather insulting, and they seemed to think that I was over here for employment rather than business meetings.
Getting into China the following week, on the other hand, was a model of efficienty and politeness...
I currently live in eastern Washington state. Up until around 2003, I lived in Seattle. In 2003 and in prior years, entering Canada was as smooth as could be. The people at the Canadian border checkpoints were friendly and asked minimal questions. I always found my re-entry back into the U.S. to be a more rude, though not particularly arduous an ordeal as going the other way.
My most recent entry into .ca was quite the opposite. Bear in mind these are very rural crossing points, nothing like the I5 transit. The most recent Canadian agent was somewhat gruff and unpleasant, asking quite a few questions. Come to think of it, in a prior .ca entry, with a female friend from the UK, the Canadian agent seemed to be convinced that we were entering Canada for the purpose of getting married and asked us repeatedly whether we had such plans. After multiple denials, he went on to advise us not to do so anyway. What??? My crossings back into the U.S. from Canada very recently have been fairly painless compared to going the other way.
I've had nothing but good experiences crossing the border at the Thousand Islands Bridge or Massena, NY. Both ways, everybody was kind, friendly and patient. I hear nothing but horror stories about Niagara falls and the one time I flew into Vancouver was less than pleasant.
I've also been subjected to extensive physical searches of all my belongings. (And just to be clear, I'm a healthy, Caucasian, 20-something, US born-and-raised, male.)
I often think of most Canadians as being friendlier than a lot of people around the US, but immigration and border control aren't one of those areas.