In the grade-A review of Mazzucchelli's "Asterios Polyp," Sean Howe of "EW" mentions the "nearly subliminal color symbolism" in the book. The symbolism is anything but subliminal -- it's an essential detail that's commented upon within the text. That doesn't make it any less great, though.
But it's like saying that the bat motif in Bruce Wayne's life is subliminal.