Customs officials are notoriously strict law enforcement officials. I've made a fair share of border crossings in my day, and while they usually go easily enough they are always a slightly stressful experience. Even when you aren't guilty of anything, having someone question your right to enter their country (regardless of whether or not it's also your country) is disconcerting.
There isn't a lot of difference in the efficiency of Canada Customs officers and United States Customs. The main difference is in their focus. Coming into the U.S., customs officers are worried that you are sneaking into the country to work. They don't ask you what you are bringing into the country (unless it's for business), and they don't try to collect duties. Canada Customs is the opposite. They aren't so worried about whether someone is sneaking into Canada from the U.S. to work, they are more worried about what you are bringing into the country, and whether or not it is taxable.
Canada Customs has also been known to collect materials they deem objectionable, even when the materialize are actually legal. In one particular case I heard about (but can't remember all the details), when the court ordered Canada Customs to return the materials, they had been "accidentally" destroyed. It sometimes seems that Canada Customs is a force unto itself.
So, with that in mind, I present the following poster that I found on RPG.net (click on the picture to see a larger version of it):
4 Good Years
3 months ago