Okay, I'll give an example here, one of the ones I remember well:
So, there's this building, right. A bit like a house, but kinda long, with an odd wood path going alongside the length of it. The building itself is made of some sort of dark wood.
Where is this place? On some road? Nope. On some hill in the woods? Nope. Floating in a void entirely by itself? Yes indeedy. But not just any void. Instead of a blank white or black space, it's all pink & purple zigzags, flowing wildly... that's the "background" in the void, I guess.
No idea what the heck I'm doing there, but I float towards the house. There is no gravity here, so once I get there, movement along the path is done by grabbing these odd little poles and pulling myself along them. Why is it that way? Heck if I know.
I do this until I reach the door... the entire place still lit by the zigzag void (which is very bright and vibrant), and then I open the door. What's on the other side? A seemingly infinite space, full of nothing but floating red and silver spheres. Blue swirls pass between them randomly. The whole place pulses, if that makes sense. A bit of time in here, and then I woke up.
That's pretty much par for the course. Warped locations and twisted geometry and a complete lack of anything making sense.
Not rare, either. I dream pretty much every single night.
