Why do guests avoid the seventh room?

In Edgar Allan Poe's short story "The Masque of the Red Death," Prince Prospero has gathered his friends and sequestered them within an abbey in order to protect them from the epidemic of the "Red Death." After five or six months of isolation, Prospero decides to throw a masked ball to entertain his guests, complete with an imperial suite of seven rooms. 

The seventh room is described as being covered in black velvet tapestries and...

In Edgar Allan Poe's short story "The Masque of the Red Death," Prince Prospero has gathered his friends and sequestered them within an abbey in order to protect them from the epidemic of the "Red Death." After five or six months of isolation, Prospero decides to throw a masked ball to entertain his guests, complete with an imperial suite of seven rooms. 

The seventh room is described as being covered in black velvet tapestries and carpeting; it contains a giant ebony clock which emits loud music as each hour passes. Only the windows stand apart from this dark color, with their panes taking on a "deep blood color." The lighting which comes from the hallway illuminates the room to "ghastly" effect and produces a wild facial expression on those who enter it. Thus, guests avoid the seventh room simply because it is terrifying--a stark reminder of the plague which has wiped out the population outside the abbey's walls.