Obviously all fairs are different, in regards to quality of care given, and quantity of birds.
The best thing you can do for those chooks is become part of the volunteer staff in the poultry barn. I've been showing 7 years, and our local fair requires the birds to be there 4 days. I am an associate director with the Halton Agricultural Society & part of the poultry committee for our fair. I was there for all 4 days & helped feed & water over 600 birds. These birds were mostly in good condition when they arrived, yet we lost 3 over the event. Feed & water 4 times a day on a schedule plus spot watering by a team of 6 volunteers throughout the day.
My birds were all fine, and they were cooped up in small cages for 4 days. At home they free range & live in LARGE dog crates in my hallway. I think we all need to realize that birds that are stressed at shows were probably stressed at home & in poor condition before they ever made it to the fair.
If your fair is not treating the birds properly....DO SOMETHING. You CAN make a difference.