Hermione didn't help matters by snorting audibly as she used her wand to scoop up all the rubbish on the floor and send it sailing to the bin.  She even knew some charm to compress it down so it all fit with room left for more and Draco briefly escaped from the horror of asking Pansy if she and Jean had exchanged bodily fluids by admiring Hermione's prowess as a witch.  She really was quite extraordinary.