In that case, the proximate causes of property-value loss will be esthetic blight (from the feces and urine dropped onto the houses by the pigs flying overhead), the need to redo the ductwork (to tailor the air conditioning and heating to fit a sun that rises in the west and sets in the east), and a glut of new real estate coming onto the market (after local Catholic churches close up shop in response to His Holiness' conversion to Paganism).
It may, however, be somewhat offset by housing demand from imps and demons in search of new abodes (after fleeing from the ice and snow blanketing their old digs).
That was a funny post.