As a converastion piece sure, if you feel a need to explain yourself to others. Don't kid yourself that you are going to eliminate a lifetimes worth of toxins on a 40 fast. It's just a great start. In my expereince the tongue thing is not a real reliable indicator.
It's always going to be a "work in progress". While the MC is a great overall cleanse you still need to address other areas as we have mentioned liver, colon, parasites each with their own dedicated cleanses and as I have mentioned often what you do in your regular everyday life post cleansing