The faeries art of concealing their true appearance is called glamour and is often
used to conceal mortals, they can alter their own shape as well as the appearance
of food, money and surroundings. So a splendid feast spread out on a beautiful table
could be nothing more than nuts and berries laid out on a log.
The term glamour comes from the Scottish word glaumerie which means magic,
traditionally this power was used to capture mortal partners for breeding.
As mentioned before faeries are always trying to improve their own race by mingling
it with human blood.
The use of faerie ointment on your eyes will reveal them in their true state but
be careful, their wrath can be terrible!
'Faeries and Folklore of the British Isles'