As someone who is also into creative writing, I just have to say what an awesome job you did. I know first hand how hard it is to create a good poem that isn't tacky, which you've achieved. The connection with art and the colors of Missus Bin's guests' parts was something I thought was really clever. You also have the art, sound effects, and music which definitely adds to the quality. Just fantastic all around. Perhaps my review is a little biased since creative writing is a passion of mine, but no one's perfect.
The only criticism I can offer without sounding like an elitist jerkoff is that the flow of the 3rd and 6th line in your first stanza I have an issue with: "always pondering the next thing to eat." The 'always pondering' bit is a little too long-winded/clunky for my taste.
Excellent work nonetheless. As a side-note, your "secret" was the icing on a very delicious (and spooky) cake.