In what ways is the unnamed narrator of "An Independent Organ" suggested to be possibly unreliable?

Early in the story, the unnamed narrator himself tells the reader that "the portrait [of Dr. Tokai] that follows is not based entirely on fact" (77), admitting that a certain amount of the story is conjecture. He states that the conjecture had come from his "own observations of things that might be true" (78). As a result of these early admissions, the reader is urged to take the narrator's words with a measure of dubiousness.