Unless you think a fishbowl is an example of great poetry, that's a contradiction in terms. If a work is no more "poetic than a fish bowl" then it's not in fact "poetic" at all, which is the same as saying that the work in question was not "poetic". Therefore it's not possible for a work to be "overly poetic" since you've actually defined "overly poetic" as the same as "un-poetic".
That's no different than saying that something which is "overly strong" is actually weak, or something which is "overly hard" is "soft", etc. etc.
I think what you mean here is that when an artist self-consciously sets out to be poetic, they often don't succeed at all, whereas when an artist sets out to express some powerful aspect of the human condition, and does so successfully, that their work may achieve being beautiful and "poetic".
I also love works that permit interpretation and can tear you in different directions, but always within the emotional playing field that was intended by the artist.
Dicksee's Yseult tugs your feelings between sympathy for the beautiful queen who has sent her agents to thwart the unfaithful plans of her husband, the dying King Tristan, from seeing one last time his unrequited lover. Is she the victim or victimizer? But I don't think any one will look at that work and think of being bored, baking cookies or the 67 Mets. While the meaning may be unclear, it's really quite clear what is unclear. Even if you don't know the story, there is a limited range in which one's interpretations can reasonably vary.
