Hi Derek

I think maybe you're doing our host an injustice.  Of course zombies are all dark inside. They are defined as being so. Are you suggesting they're not?   

Consciousness is certainly difficult to define. I don't think anyone would disagree about that. It is one of the benefits of the zombie hypothesis that it draws attention to this problem. What is it we have that zombies do not? If we say, with you, that we can't define this phenomenon well enough to even ask this question then the zombie hypothesis has done its job, focused our attention on the heart of the problem and drawn it away from the superficial aspects.   

But a distant planet populated by zombies is unnecessary. We could equally well hypothesise that everybody except ourselves is not conscious, for the zombie hypothesis is just a reformulation of the other minds problem. It raises no new issues that I can see, but it's catchy way to think about them.