I can't claim to be able to detect LLM writing with 100% accuracy, but when I do notice it, it's very off-putting. Some claim that's because it's bad writing and that I would be fine with a higher-quality generated text, but that isn't true. I dislike LLM writing purely because it's generated by a machine, not because it's bad (though the bad quality does make it more jarring). In my opinion, handing other people something that a machine generated for you and asking them to read it is extremely disrespectful. I want to read what the human wrote, imperfections and all, because humans have intrinsic value that makes their work matter to me. The product of a machine, on the other hand, is just a facsimile trying to appear like a human made it, and that holds no interest at all to me no matter how good the content would be were it man made.