Can You Clean Like That?

"I cleaned like a demon in there." (Sally, 90)

When Clarissa comes home from vising her ex-boyfriend, she meets Sally at their appartment. Sally being the good girlfriend she cleaned the house for that evenings party. Cunningham uses a simile to relate her cleaning speed to a demon. 

Analysis:

At first I thought this simile meant that the character of  Sally did not clean at all since its being compare to something that the least thing it wants to do is clean. Therefore I concluded that what the author meant to say was that Sally had really cleaned up their apartment just in time before Clarissa was in. What tied my conclusion together was how a demon moves. A demon moves fast and aimes for its target with no hesitation and that was exactky what Sally had done with the room.