These days they are, no matter what direction your going. The amount of information at their fingertips is astounding. That includes reviewable video. I know people who suffer the consequences every trip after being labeled in the system. With my family being split between American and Canadian citizenship and living on both sides of the border, I won't do anything to jeopardize my freedom of movement. It's just the way it is today. As far as replacing tires blown out, replacing bumpers, etc., there is nothing to stop you from doing so, but you must answer all questions and the Customs Officer will determine if a secondary inspection is warranted. One question is always, "did you buy or recieve anything"? The penalties for any infraction is very stiff...why chance it?