If, as Chalmers and others argue, the conceivable existence of philosophical zombies entails a total, or at least partial, rejection of physicalist monism, then the next and most reasonable step would be to substantiate the central idea of such a hypothetical world, in which humans lack conscious awareness yet resemble ordinary humans in every way. For my part, I have a difficult time imagining how this is even possible, since it seems highly unlikely that our ordinary course of action can be separated from the sense perception which so strongly influences our everyday behavior.
Even so, as I was considering this problem throughout the course of the work day it struck me that certain forms of automatism, such as sleepwalking, potentially provide real-life examples of situations in which ostensibly conscious humans act and speak as their truly aware counterparts without experiencing any significant form of consciousness themselves. Why this line of reasoning isn’t more common I don’t know, though I must grant that the possibility of being entirely off-base may be a reason that more philosophers haven’t brought this point up. Nevertheless, if the more extreme forms of automatic conditions are taken in their entirety (such as sleep driving, somniloquy, sexsomnia, etc.), then it would seem that the plausibility of the dualistic arguments based on philosophical zombiism is at least somewhat strengthened.