PAXboy, lots of people travel with things they think will be useful when they get to more distant places. One of the favourite items used to be camping gas cylinders. I've also seen real and imitation firearms (undisclosed) as part of checked baggage. Personally, I have offloaded smoke flares, rockets, magnets, bush meat etc... And then there's the return trip. "Cor, you can't half buy cracking fireworks in ... (Fill in Spain/Greece/Turkey/etc.), I'll take some home for Guy Fawkes Night!" And then there's those who make genuine mistakes and unwittingly take things they didn't meant to.
So yes IT HAPPENS ALOT!