A Skillful Method to Ensure Rebirth into Western Pure Land

[sinweiy]

Various Realms Viewed by Earnest Practioners

49) Internal Realms
50) External Realms
51) Discussion on Demonic Realms <---
52) Various Types of Demons

http://www.ymba.org/BWF/bwf70.htm

[Nosta]

From the link provided above by Sinwei:

51) Discussion on Demonic Realms

As indicated above, sometimes the Buddha Recitation practitioner sees marks and forms which could actually be demonic realms. These are instances where cause and effect do not correspond. For example, while visualizing the physical features of Amitabha Buddha, a practitioner may suddenly see the features of a beautiful woman. Another cultivator, diligently reciting the Buddha's name in the hope of seeing auspicious scenes of the Pure Land, may unexpectedly see a slum area, with men, women and domestic animals running back and forth in all directions. Yet another practitioner, hoping to see precious lotus blossoms in the Pure Land, suddenly sees a small cart instead. These are demonic realms, as cause and effect do not correspond.

[Nosta]

I think that there is a good answer for the question about bad dreams after recitating in the same ebook that Sinweiy talked, but in another section:
http://www.ymba.org/BWF/bwf73.htm#dreaming

Here it is:
"If the cultivator has followed externalist ways in lives past, he usually sees his body emitting electric waves, or his soul leaving the body to roam, meeting demons, ghosts and the like, to discuss politics and the rise and fall of countries and empires. On the other hand, when the practitioner's mind is pure, he will know in his dreams about events that will occur three or four days, or seven or eight months, hence. In general, those who have cultivated in previous lives will immediately see auspicious realms when reciting the Buddha's name. Those with heavy karma, lacking merit and virtue, will usually see evil realms when they begin Buddha Recitation. In time, these evil omens will disappear and gradually be replaced with auspicious omens."

(the underline is mine)