For an example of the right way to offer criticism as an expert judge, look at Jacques Torres on Nailed It! The bakers are all horribly incompetent, but while the other two judges are happily dunking on them for laughs, Jacques explains to each one what went wrong with their bakes and how they could fix the problems. Even when the food is dangerously inedible he remains gracious.
I think Zac can be poisonous sometimes, encouraging the other judges to also be nasty to the contestants. I'm glad Lorraine Pascale decided to stay on her side of the Atlantic for a while instead of coming back t