Um, it happens. Kids who are arrogant, not nice to the counselor, bullies, grinds with no personality. The LOR may not be terrible, but it can be bland. AOs know how to read between the lines.
Also, I was asked to assist a high-scoring, High-GPA student with his essay. It was terrible. He really did not know how to write well or how to present his ideas. I tried to inspire him to improve it and provided guidance. He made it better, but it still wasn’t very good. He got rejected outright from Tulane.