COOKING UNDER PRESSURE
It's been said that cleanliness is next to godliness. When it comes to chefs teaching public classes, they should make that their motto. However, I think when they get in front of an audience, they get too busy to pay attention to their sanitation habits.
I've been to a couple of cooking classes where there were some pretty shocking examples of not living the godly life.

Tasting: It's the core of being a great chef. The food has to be tasted and tasted and tasted. Please, chefs -- use plastic spoons and toss them after each taste. Plastic spoons are cheap. Double dipping is gross. And, yes, I did watch a chef at a class use his tasting spoon over and over.
Plastic gloves: Are a good thing, but they must be changed between tasks. Again, I watched a chef French ribs of rack of lamb, then wipe his gloved hands on a cup towel and turn around to "stir" a pan of roasted peaches without changing gloves! That's gross, too. It wasn't like the chef only had one pair of gloves. He had brought a box of them to the class.
Cross contamination: Don't use the cutting board for fresh food that has been used to cut raw meat. No it's not good enough to wipe the board off after smearing blood all over it. It has to be sanitized with bleach, rinsed and dried before using it again to cut up fresh veggies.