baymule
Garden Master
I would tell her that you know that she has a very high level of expectation for the appearance and health of her dog which is obvious since she is bringing it to a professional groomer. Because of that, you can not risk your reputation to the use of substandard products, techniques or tools and that you will be re-bathing the dog so that it's coat is properly prepared for the rest of it's grooming.
... might even have to charge more for the soothing oatmeal shampoo you will have to use to keep the coat and skin from being dried out with all that extra bathing....
Only one word for this...... BRILLIANT!