A normal demand curve (which when graphed goes down and to the right) shows that when prices go up, the amount of a good that is demanded goes down. Examples are when the price of gas goes up, people buy less of it and do less driving. ... An exceptional demand curve is one wherein the opposite occurs. it is a demand curve rising upwards showing that people buy more when the prices go up. the following are the reasons for an exceptional demand curve;

Inferior goods/ Giffen goods

Goods having prestige value

Price expectation

Fear of shortage

Change in income

Change in fashion

Basic necessities of life