I'm a white belt (just have been traing three weeks) but I've watched my daughter's classes and some of the sparring classes for 8 months.
We have sparring during class about every other week (part of the curriculum for the whole week). There are also sparring classes for Black Belts and Black Belt Club (BBC) members twice a week.
I saw a brand new orange belt female, who had just joined BBC attend her first sparring class. She paired with a black belt. He hit her in the side of the head. Kaboom! She hit the ground. She was dazed. I don't know if he actually knocked her out. She is small, short. He's tall and built like a brickhouse so it would be easy for him to knock most newbies down. I know he's used to sparring with some of the other black belt males or more experienced females. I saw him spar at a later class with a black belt female. He knocked her down, too. She seemed a bit angry with him so there may be more going on. She's a black belt so she knows what to expect in sparring. I don't know to what degree men hold back when they spar with a female? Should they?
We do have one teenage orange belt, "D," who is very uncontrolled with his kicks. The rumor is that he also likes to "pick on" the lower belts. We do know the instructors "usually" won't let him spar with females. Before my daughter was an orange belt, she was paired with "D" for one-on-one kicking. He kept kicking her. It's no contact - 0. One of the instructors saw him hit my daughter, came over and punched his arm so hard he almost fell down. The instructor told him, "Don't you dare hit her again!"
Just recently, my daughter was paired with "D." Two instructors were watching the entire time. I'm happy to report that she faked "D" out with a fake back fist and then sidekicked him in the solar plexus and forced him out of the ring
Well, as luck would have it, I was paired with "D" for one-on-one kicking. The kid kicked me three times. I'm not apt to complain too much because they were light kicks. But that tells me something: he knew exactly what he was doing...if he were sparring, he wouldn't have kicked me lightly. So, from that standpoint, it makes me angry because I believe he's trying to pull shenanigans, to see what he can get away with. Obviously, he's developing some control. (I have to laugh - During his first sparring class, he kept hitting his green belt partner in the buttocks with a roundhouse kick!)
Next time, "D" kicks me during one-on-one, I'm tempted to grab his foot or leg and hold onto it and watch him hop around on one leg!
I think Mr. "D" is going to be a problem. Fortunately, the instructors are aware.