I have to wonder what Dick would have thought of the whole "Deckard is an android" thing had he lived. In the novel, Deckard actually has someone else perform the Voight-Kampff test on him, and he checks out as human--no ambiguity there. (Also, it was interesting to me that Rachel's VK was the only scene in the film that really corresponded to any specific scene out of the book, and was practically word for word the same).