I think all the time in dreams, just as I do in real life. The more logical my thoughts become, the closer I am to lucidity. It allows me to judge how close to lucidity I got.
For instance, last night I had a dream in which I drank a bottle of vodka, went to a tattoo parlor, and woke up on the carpet with LOVE tattooed all the way down my back. My dream body sat for a while freaking out about this, and I started thinking, rather logically, about the repercussions of this giant tattoo - I’d have to be extra careful about the shirts I wear to hide it, especially at work; tattoo removal might be an option, though it sounds painful, etc. If I had thought a bit harder and realized how ridiculously out of character the whole experience was, I might have realized I was dreaming.
When I’m lucid I really start questioning and experimenting, my thoughts growing more complex. Does anyone else have this correlation?