The finest bullshitter I knew had serious skill and brainpower; and he BS'd about stuff he was expert in. It was really a sort of party trick - he could leave his peer experts speechless (more likely, rolling on the floor laughing).
His output was indeed word-salad, but he was eloquent. His bullshit wasn't fallacious reasoning; it didn't even have the appearance of reasoning at all. He was just stringing together words and concepts that sound plausible. It was funny, because his audience knew (and were supposed to know) that it was nonsense.
LLMs are the same, except they're supposed to pretend that it isn't nonsense.
