I gave each of my 5 chickens a bath this summer after I cleaned out their coop really well and washed everything down. I thought they had lice or some kind of buggy creature, so I used dog flea shampoo diluted in luke warm water. (Not directly on them) They actually seems to like it! They freaked out for about 1/2 a minute and then realized that this might feel good, and they sort of spread out their wings and layed in the water. I was really surprised. I brought them into my house and gave them a bath in the tub. My husband was sure I had lost my mind. I assured him I would bleach the tub afterward, which I did. They sure looked good afterward, and they didn't seem to have the need for as many dust baths so it must have done some good.
My hens are so spoiled. I really do get carried away. My husband says the farmers from Illinois (where he came from) would die if they knew how I cared for the chickens, but I don't care what anyone says. I care for them and want them to be happy AND healthy. (Nice looking doesn't hurt either).