Prior to getting my Nexus, I was 4/5 times pulled into secondary at YOW. I guess they don't like under-20's with a passport full of visas.

YOW and DTW always ask 'how can a student afford to travel so often?'. Before I used to tell them 'saving', and 'backpacking', and that usually got me pulled into secondary. Now my answer (albeit not true), is 'my Grandparents', and they seem to prefer that answer.