Honestly, I like that in a teacher? Sugarcoating's just going to make me learn slower or learn incorrectly.
I remember when I was 15 and still doing martial arts, I'd reached the highest level of black belt I was allowed to until I was eighteen, and I felt like I was hot **** because I'd just gotten #8 in the country in tournament results in the ITA. So one day I was apparently acting like a hot shot in our sparring sessions, and our instructor called time, switched me out with the person he was sparring with, then started us all up again. Then he kicked my ***, and ended up jump spin-kicking me right in the chest and throwing me into the mirror at the front of the room. It shattered behind me, and he yanked me by the arm to get away from the glass, asked, "You okay?" Then the moment I nodded my head he started beating the **** out of me again.
I love that story because it taught me humility very ****ing quickly.