I have spoken to several schizophrenics in various states whether it's medicated and reasonably together, coherent but delusional and paranoid, or spewing word salad as you describe. I've also experienced psychosis myself in periods of severe sleep deprivation.

If I've learned anything from this, it's that we should be careful in inferring internal states from their external behaviour. My experience was that I was essentially saying random things with long pauses inbetween externally, but internally there was a whole complex, delusional thought process going on. This was so consuming that I could only engage with the external world for brief flashes, leading to the disorganised, seemingly random speech.