Lots of traveling means lots of sweating, and although you may not necessarily be exercising, it's just a natural bodily function. Sometimes things are exciting, and even if you're lying on the beach- your clothes could start to smell. Naturally, you would just put them in the washing machine to freshen them up, but it doesn't always work. Scented dryer sheets are a great addition to your suitcase, even if you don't end up using them.
If you are lucky enough to have a way to do laundry, dryer sheets are a much-needed item since a wash alone doesn't always keep things smelling as fresh as they should be.