To infer stature from “ṭawīl al-nijād,” the listener needs to recognize the association between strap length and height. To infer hospitality from “jabān al-kalb,” the listener must understand the relation between frequent guests and a dog accustomed to strangers. An unclear sentence does not license arbitrary meanings.
Allusive indication depends on a recognizable concomitant or relevant relation, not an unrestricted imaginative leap. If the speaker intends an unrelated property without any understood connection, the listener has no reliable route to that intention.
The association is therefore crucial to good kināyah, whether its force is based on logical consequence or conventional usage.