At least yours behaves. Mine would kick and jump when I tried to clean her. And I'm wxctly sure... It was so long ago and I wasn't really paying attention to when it exactly stopped. Maybe about a month?
I hope it works for you too. It can take a bit of time. It's so nasty when they get dirty down there... Moisture and bacteria builds up and then they stink. Blech. I would have to go and cut some of her feathers because water and wipes wouldn't clean it.
I was having this issue this past spring/summer. My Polish always had a messy butt. I used to give them one or more treats daily, now I only give a treat every few days and she has been much cleaner. Melons, cucumbers, and foods with high water content often cause loose stool.
Wow. I'm jealous that all of you guys' chickens eat greens. The only greens mine will touch are flowers or vegetables I spent months growing... Guess they are just a picky bunch.