My girlfriend wants to run ethernet cable along the corners of the walls of her apartment, but is rather particular in that it needs to be discreet. Cable covers are NOT an option here, as the trimmings would only run up one corner of the room, then along one corner of the ceiling until reaching a wall mounted PoE (power over ethernet) camera placed over the front door of her living room. I have suggested command strips numerous times, but she insists that these are unacceptable, as they would not allow the cable to rest flush against the corners of the wall.
I've thought about double-sided tape, but she reasonably suggests that it would last all of 15 minutes before falling off the wall. This is an apartment, so drilling holes or nailing anything down is completely out of the question.