The other day, my almost 3 yr old son was being very typical and yelling at me and egging me on about some toy he wanted while I was in the middle of teaching a piano lesson in my home. I went over to my son and explained that I would help him in a minute and he just yelled back in my face. So again, at his level I told him that he needed to stop letting such bad sounds out of his mouth or we might have to wash them out! He continued to yell and throw a fit, so true to my word, into the bathroom we went and in went a minuscule amount of soap and water, but enough to taste it, and then a drink. He was agreeable after that, and we proceeded with the piano lesson.
My student (a 12 yr old boy with only 1 other sibling) looked at me and said with wide eyes, “You are the first parent I have EVER seen or heard of that actually washed their kids’ mouth out with soap!! Does it really work?” I told him the logic behind it (washing out bad words that we don’t want to hear and use in our home) and that, YES. It does work very well and that the time he just witnessed was just the 2nd time I have used that particular discipline.
It has only taken a maximum of 3-4 times in each of my children before talking back becomes very easy to deal with. So I think its totally called for.