Here is a scenario that I wrote in the post that Buckie linked to above. The idea of it relates to what my moral ruling would be.
"You have a crazy old uncle with a yellow ranger, a sequoia, and a prototype for the first Weber kettle in his yard. He's nuts, everyone knows it. You ask for the Weber stuff and he says, "You can have it when I'm dead, but if you come get it before then I'll shoot 'ya!" So you wait, he croaks, but when you go to pick up the stuff someone has made off with it because his yard was overgrown and he was too nuts to ever answer his door.
So, was that stuff abandoned, or did it belong to a crazy old fart who was going to give it to his nephew with a Weber problem when he finally kicked off? I always like to err on the side of, "If I didn't pay for it or I wasn't given direct permission, then it ain't mine to take."