This one was easy to identify as it had not been patched or gaps concealed.
Other signs can be apparent even when not significantly out of level, thought I’d share.
I’d say that one of the most common signs of rotation or similar defect is a V or tapered crack where firebox meets face of fireplace, such as brick or similar. Maybe you’ve seen repaired grout in this area?
By the way, not in Bev Hills today