I regularly travel to conventions with a checked suitcase full of merch. I, and most of my vendor friends, have an ever-growing collection of these things. We all seem to just leave them in our bags for next time.
I mean, yeah, they don't have to be leaving it, but experience shows that they do.
The only way to really be sure is to only travel with carry on luggage and never let it out of your sight. Obviously this is not always feasible, but, I think people do a poor job of packing carry-on luggage and assume they need something huge. You can definitely make due with surprisingly little, and it's easier to get around the airport, etc. If you have something big to bring home, just have it mailed to you.
I regularly travel to conventions with a checked suitcase full of merch. I, and most of my vendor friends, have an ever-growing collection of these things. We all seem to just leave them in our bags for next time.
I mean, yeah, they don't have to be leaving it, but experience shows that they do.