Grandmother Mountain boulders in western NC, me and a buddy had to cut a climbing trip short after getting into some shit with a four pack of the locals over me taking photos of some of the problems there. Nobody got hurt but it was every bit as hostile as any encounter with the surfing locals I'd ever had in the Outer Banks.

Vedauwoo Wy, a local friend made me leave my camera at his place and basically warned me not to talk to or even make eye contact with any of the locals at some of the back country crags we were going to. No encounter there but the stories I've heard told (and believe) are something else. Same for Wild Iris near Lander.

There's a crag in MA where the access is specifically conditioned on the crag not having a guidebook or the routes being recorded in an online database.

I don't know of any violence occurring over any of this, but I know there have been access issues and closures in the past.