I handed the work back marked up, and I could see the confusion on her face, she genuinely thought she'd done it right. The truth is I'd never told her what "right" looked like; the standard was all in my head. She only found out where the bar was by falling short of it, and that's not really fair to her.
More people experience this than they realize.
You hold your team to standards you never actually told them about.
If this sounds familiar, the Library can help you find the bigger picture.