When flying back from the US I left my laptop in my carry-on bag when it went through the x-ray machine - I was sharply asked why I didn't take it out and put it the tray - "because no signs or people told me to". A more pleasant man then swabbed it (no disassembly required), and was apologetic when he took my wallet from the tray and accidentally tipped all my loose change onto the floor, we had a good laugh scrabbling all over for it.