Like in the cases of US courts defining obscenity or fair use, there isn't necessarily a set of metrics which can be used to perfectly taxonomize something.
Imagine I sent a manuscript to a publishing house and they rejected it for being bad. I wouldn't expect they got to that conclusion by comparing it to a set of metrics, I would assume they have people in authority whose judgement is the decider on whether something is "good" or "bad".
Imagine I sent a manuscript to a publishing house and they rejected it for being bad. I wouldn't expect they got to that conclusion by comparing it to a set of metrics, I would assume they have people in authority whose judgement is the decider on whether something is "good" or "bad".