My biggest problem is consistency and attitude, I see some who seem to have a bias but not many. I'll give one example of attitude: We were at a Christmas tournament, out of town and down by 4 late in a game, the other team is at the line shooting free throws and my son told his teammate "I've got shooter" The boy shoots and misses the ref jumped up and called a lane violation on my son for talking to the shooter. My son tells him "I was telling my teammate that I've got shooter and he hadn't even shot yet" With everyone still at the line the ref points his finger at my son and says "Boy don't complain to me because you are losing or we'll make sure you lose" In my opinion, a guy like that has no business reffing high school ball. Now I admit I'm biased to my son and his team but I really don't understand how you get in a 17 year old's face like that in front of players on both teams and say something like that.
As some mentioned above about big guys getting foul calls more, I see that with our big guy too, but I also see that on other teams. Just because a guy is big doesn't mean he is fouling more, if its not a foul on a normal size guy, it shouldn't be a foul on the bug guy either.