After Deaton hands the Stiles the vile of powder, it goes from his hand to the table and back to his hand.
Heather screams several times while she is being attacked and several bottles of wine are shattered. While the wine bottles may have been an illusion created by the Dorach and confirmed by the fact that Stiles doesn't notice anything amiss when he returns to the cellar and there is no broken glass or spilled wine to be seen, Scott would have surely heard the screams. Yet no one knew anything was wrong until the next day.