I have always heard that the Canadian customs are polite...
but also a pain. Also, cameras view your car and they plug your license plate into the computer. I was told recently that once you are stopped and searched extensively, you will *always* be stopped and searched, because your car is "marked" by the computer. Don't know if this is true.
Coming back to the US, the US INS was using drug sniffing dogs. Cars would be told to open their trunk, and the dog would be invited to hop in and sniff around