One of the issues that makes this murkier is that it is often only social norms and expectations that determine whether someone is misrepresenting themselves. In the meme world, the whole purpose is to share and modify slightly. There isn't an expectation that your post is original. In the academic world, every single word is assumed to be original unless cited otherwise. There are areas in between these cases, and often what someone calls a violation is merely the case of someone misreading the social norms.