Three years ago I was flying HKG to SEA via YVR and US customs did not like the fact that I had two passports so they sent me to secondary where they went through all of my stuff. About half way through, they came to the realization they would not find anything so quickly finsihed up. What bothered me the most was in the process, I overheard what was going on to the person next to me. The guy had a book called "understanding Islam" or something like that, I had no idea what nationality he was but the Customs guy strongly recommend that he toss this book into the trash and the guy did!