Personally, I don't mind if any photos or information is copied from my tree, which is public. If people enter it wrongly into their own trees, that's up to them. It's their responsibility to make sure that it's entered correctly, and for others to make sure they're not copying a load of ol' rubbish, as is commonly seen in many online trees...as long as nobody defames any of my ancestors.
I object to people with private trees being able to take stuff from those of us willing to share our findings openly, but not offering their own in the same manner. It's one-sided, and I put it to all of you private tree owners that you're not entering into the spirit of the genealogy community. I wish Ancestry would put measures into their website to prevent people with private trees being able to chore stuff from public trees.
Recently, I requested politely (almost on bended knee, as though I should have to crawl) a useful image someone had in their private tree. It was a parish register of the marriage of a certain lady to a certain gentleman, both in my public tree. All I got in response to my request, from the woman who owned the tree, was, "This lady was my aunt." Well, very interesting, yes, truly, but where's the image I asked for? Despite several polite, webmailed, correspondences via Ancestry, I'm still waiting.