How does the ghost explain the behavior of the Otises?

The Canterville ghost is both disheartened and angered by his inability to frighten the Otis family. Furthermore, they appear to mock the ghost by offering him medicine when he wails along the corridor and they remove the bloodstain with cleaning products. For the ghost, there are only two possible explanations for such behaviour.

Firstly, the ghost believes that the Otis family are "horrid, rude, vulgar and dishonest," as he tells Virginia in Chapter Five. Lacking all morality and decency, the Otis family mock the ghost, outwit him at every possibility and generally fail to appreciate his role in the house.

Secondly, the ghost believes that the Otises lack the necessary skills to appreciate the history of Canterville Chase and, more generally, the existence of the afterlife. As he says at the beginning of Chapter Four:

They were evidently people on a low, material plane of existence, and quite incapable of appreciating the symbolic value of sensuous phenomena.

This idea is illustrative of a wider theme in the story: that the ghost and the Otises cannot live harmoniously because of a deep-rooted culture clash. The ghost, representative of the old world of the English aristocracy, finds the beliefs and manners of the American Otis family abhorrent because they represent change and the development of a new worldview.

It is, however, interesting to note that the ghost is forced to enlist the help of Virginia Otis in Chapter Five. In this respect, Virginia is symbolic of the reconciliation of these two ways of life: she brings together the old world and the new, enabling the ghost to finally leave Canterville Chase and rest eternally in the Garden of Death.