The care and feeding of food critics is a tough row to hoe. Especially when those food critics are your family. We have a rating system for food in our house. A new dish is under scrutiny by the entire family and each rates the dish from 1 - 10. A perfect 10 means that we are eating a "make it again and often dish". A rating of five means that it is just okay; it will be neither missed nor requested. Below five indicates that the dish will not be made again. Dishes that are barely edible, I've made a few, are given a one. A score below one and in the trash it goes. I've never served anything that threatened their health, just their sense of taste.
Except for my youngest, my children tell me specifically what would improve a dish in their opinion. It is much easier to listen to their comments than to hear gagging - intentional or not. They have become more articulate as they grow and now they are more interested in making their favourite dishes. My youngest still uses the Roman Emperor signal - thumbs up for great and thumbs down to indicate trash can contender.
I think this system works. My children will testify that I haven't made an all out gagger in a while.