Yes; that's what I said.
You can be fooled into thinking you are not dreaming, even though you are. But not persuaded that you dream, when you are in fact awake (and in your right mind -- not hallucinating or delusional or in some other "living sea of waking dream" as John Clare might put it).
The two situations are not symmetrical.
Ok, I take your point. However, that does not mean that the brain is not capable of running its model fully formed on its own (right down to feeling solid objects that are not in fact there), merely that it is normally able to tell on some level when there is real input coming in from the senses, and when it is itself making up this input.
It's a sensible safeguard for animals that dream to have a way of telling that reality is not a dream. Less important from a safety point of view to be able to tell for sure that you are dreaming when you are dreaming.
ETA: In fact, this isn't quite right. The important point is that it is possible to be completely fooled over an extended period, while feeling yourself to be entirely lucid, by a made-up reality that may, in fact, not appear to be odd in any way – no people turning into mirrors – and then only to realise (at first the realisation may begin simply as a doubt) that this is not reality when something a bit weird does happen.
An explanation for this – the one that I feel is the most coherent – is that the brain runs a model of reality into which it feeds the input from the senses to generate our experiences (all of them). The information is always incomplete, and we are well used to filling in the holes, such as our visual blind spots. When it is very affected, it is possible for the brain to make 'best guesses' about the missing input, as it always does with the blind spots, and continue to generate experience. The guesses will sooner or later prove to be inadequate (more often sooner, but not always) and our 'knowing self' will realise that this is not real data. The model would of necessity need to be dispersed across the brain as all the different representations are made separately and combined to produce our sense of a coherent, complete, ever-changing now. (Once, with a high fever, I had the hugely disconcerting sense of things that should be happening simultaneously happening one after the other. I had the very scary feeling of my sense of self disappearing. I have heard people speak of a very similar thing happening during a psychotic episode. The ability to combine all our disparate images into a coherent whole seems to be central to our sense of self – the feeling of what it is like to be us.) I would guess that the rules would need to be coded from birth, not learned, found somewhere in our DNA. That's where I would look for them.
Given that our different representations are generated separately, it is remarkable indeed that we should be able to make up data that all comes together as a coherent whole. It is an extraordinary feat of processing. But what else could be happening? Where the model with rules has explanatory power is that as the real data dries up, the lucid experience following sensory deprivation or disassociative drug taking will take up where the last set of good data left off. The remembered last reality is taken as the starting point and the 'program' run from there.
This may not be right, of course. We may simply have learned from a lifetime of perceiving how things ought to go and be able to trick ourselves in this way. But where is the story made? How are all the parts of the story brought together into an integrated whole? How do we coordinate all these different images that we've made up?