I would give everyone a home test - program X or Y in one of languages (L1, L2, L3). And I would watch:
a) the overall quality of the code and documentation,
b) whether the person asked about intentionally vague part of my request,
c) how much of the code was taken literally from StackOverflow or other source and whether the person acknowledged it,
d) whether I received the solution from them in the last hours before deadline or a bit sooner.
This, taken together, would tell me much more about that person than a highly technical and esoteric interview.