Be ware of playing favorites, or anti-favorites. One of our sensei's has an obvious dislike for a student he feels 'doesn't try'. He pounds on him (yellow belt) and picks on him. On the other hand his (sensei's) wife is also in the class and he pays far more attention to her than other students. For example he'll watch 4 people do the same kata and the critiques will go, one for wife, one for the other three in general, one for wife, one for other three in general etc. She's a very good karate-ka, but that's partly due to her always receiving specific feedback on all of her tecniques while the rest of us just try to apply the general stuff to ourselves. It's a small class, so there is plenty of time to critique everyone in detail.