If one has consumed foot bath water or guru toe nail clippings, one has crossed a huge boundary marker.
Disgust is hard wired into our nervous system. Its of the utmost importance in assisting us to maintain boundaries.
Tamper with someone's disgust by persuading them that consuming toenail clippings is a honor and blessing, and that person's boundaries will be disrupted in all kinds of ways.
And imagine the price of waking up and changing one's mind. One has to live with the horrifying realization that one was persuaded to consume vile products of the guru's body. One would likely feel horror and disgust, not only towards those who conned us, but also would feel horrifying self disgust as well.
Many would stay locked in rather than face all this.
For more research on the neurology of disgust read here.