Interestingness and meaning have a strange relationship. On one hand, an interesting thing is a thing whose meaning we want to understand. On the other hand, the pleasure we get from an interesting thing comes mainly from the effort to grasp its meaning, not from actually grasping it. Once we have a satisfying, reliable understanding of a thing, it stops being interesting.
For me, finding something interesting is usually immediately preceded by a "poof" moment, when the tentative meanings I've been applying to it have suddenly exploded into a cloud. The meaning has become, not shapeless, but diffuse, composed of interactions between lots of elements I can no longer keep fixed and separate in my mind. It feels as though the image of something true and important has burned and I'm trying to condense the smoke back into its previous form.
Which means there's both means and motive to explore, discuss, argue, write, think about; the post-facto signs of interestingness.