I've been fortunate and never had one stolen. But I think about it everytime I want to leave on in the woods. Unfortunately, I rarely leave one set up because I don't want to loose it. And this puts me at a disadvantage.
It is a real shame that unethical hunters steel from us ethical ones. Although its not just hunters doing it. I know of one person that had a stand stolen off of thier property by a non-hunting neighbor. The stand was recovered under a pile of brush behind the neighbor's house.
This neighbor is one of those guys that has very little land but pretends he owns the entire woods. In the middle of hunting season this guy will let his kids ripp all over on a dirt bike and 4 wheeler (on other peoples property) but flips out if someone else puts a stand up even close to his property line.