I had one many many years ago and it wasn't watch related. Bought something from china off ebay and the seller marked it as gift with a nominal amount. so far nothing really that unusual right? well, customs got a hold of it and put a "NOT ALLOWED INTO CANADA" remark on it because the declaration was not true to form. it was not a "GIFT" and was essentially misrepresented on a legal form.

I found this out by following up with customs. this is what they told me. got my money back from the ebay seller eventually, minus all the service fees, so I got like, half the amount.

that was my only incident with customs. all other transactions went alright. I had I think one or two where I had to pay duty and taxes.