I occasionally bring things home in cardboard boxes if I don't have a spare suitcase. On nearly every occasion, I get stopped at Swiss customs and asked what's in the box and how much I paid for it. They're always very friendly, but they never seem to miss a penny of duty if they can collect it...

Got caught returning from a trip recently -- had an item that cost about CHF380- packaged in a box, and had the receipts ready to go as I knew we would get stopped for secondary. My wife and I had planned to split the item over our duty-free allowance of CHF200- per person, so I was feeling quite smug.

...until the Customs guy told me that you can't split individual items. So we paid duty on the full 380.