I've been listing items as Free Stuff on Craigslist for years and my late husband used to joke that if we went to the weekend flea market at the old drive-in in town we'd probably see half our stuff. I did have one guy e-mail me a picture of the giant rug he'd hauled away- settled in his living room with his dog resting on it.
Like Calico, I'm female and live alone so I leave things at the end of my driveway or on my front porch.
I've given up on holding things aside for people- too many no-shows. I just say the first to arrive gets it and I'll delete the ad when it's gone. If it's a heavy item I also tell them I'm a lightweight and can't help them load it into their vehicle.
Finally- I discovered that when I carefully list the item in separate listings because they're in different categories, the first to arrive usually grabs them all- confirming the reseller hypothesis. I've since learned to add in small items that I haven't listed. They disappear, too!