I often cringe when I see the responses to a forum post on how to carry a Sony 70-200mm f/2.8 or Sony 100-400mm. People seem completely oblivious to the damage they are doing to the mounts on their cameras. Worst yet, they are happily advising other users to do the same.
How do you know whether to reconsider how you carry your camera/lens combination? If it comes with a lens collar that allows for attachment directly to the lens, the rule of thumb is to use the lens attachment as these lenses are likely to be heavier than the camera body.