פירוש על עבודה זרה 40:6

The Talmud points out that when it comes to the prohibition of watching animals mate, the owner may bring animals to mate, and even watch the full intercourse to make sure that it happens. The prohibition is waived because the owner is not interested in sexual arousal, he is interested in his work. So too in the case of the launderer, he is interested in the work. But other men may not look at new colored women’s clothing.