Cheap knock off nightmares

Last night I woke up about 5am to my phone buzzing, mightily confused. A little disorientated and blurry. The phone shook me out of a nightmare.

Now the weird thing is there was this bit where I put an old rusty key in a oak door and the whole wall just melted into black ooze. Standard nightmare stuff.

But this is what confused me. The black ooze kind of looked completely CGI, a bit fake, a bit plastacine. It never struck me that you could get cheap CGI effects in dreams. It kind of puzzles me for some reason I don't get.

The reason is probably boring but the question is kind a curious.