Anosmia

Anosmia is the complete lack of ability to smell. It can be a congenital defect or it can be attributed to a brain injury, illness, or the aging process. Because smell and taste work together, people with anosmia lose not only their ability to smell but also suffer a marked loss in taste perception. They can taste hot/cold, spicy/not-spicy/, sweet, salty, sour, and bitter, but they can't detect other differences in flavor. A raspberry and an orange taste the same. Vanilla flavoring and spices cannot be detected. Food textures become most important to people with amnosia. 

In the case of the girl from the youtube clip who has congenital anosmia, smells are associated with temperatures. If someone tells her a room smells badly, she feels that the room is warm. Although she does not see it as a real hindrance to her life, the loss of smell can be dangerous in certain cases. Leaking gas and burning buildings will not be noticed unless the anosmiac can see the gas or flames/smoke. They have to pay closer attention to expiration dates because they won't be able to tell by scent or taste if food has gone bad. 

http://www.youtube.com/watch?v=LH8SLuTTd4k