See YD 95:4 Here:
http://hebrewbooks.org/pdfpager.aspx?req=9145&st=&pgnum=435
Mechaber holds if you wash pots which contain meat and milk in the same pot, we can be meikel as long as there was also ashes (soap) in the pot.
Taz, 95:14-15 is skeptical. He says if so it should be muttar if you wash your pot with soap that is made of non kosher fat as long as the soap contains ashes. He does not buy it.
Yet, the heter is accepted. Generally, we will say if there was soap present in any issur, it is muttar bdieved.
I don’t even think the soap should be a problem lechatchila, since the soap is already made, and itself is already b’dieved. (I am speculating)
I would eat the soap.
(Contrast 103:1-3. An issur which creates an unpleasant taste does not make a food assur. 103:1. Even if it only creates an unpleasant taste due to the presence of a third ingredient. 103:2.
Apparently, the case in 103 is that due to the presence of the third ingredient, the issur actually did impart unpleasantness. In 95, the issur is still adding pleasant taste; it just happens to be mixed together with the unpleasant stuff.)