I'm no expert but aren't you exposing one patient to the previous patient's poop? There could be anything from a lovely c-diff payload to something the next guy is allegeric to like nuts. As a layperson it hardly seems harmless.
https://www.focusforhealth.org/need-a-colonoscopy-the-one-qu...
Something that looks unclean can be sterile and harmless while something sterile and visually clean can be incredibly harmful as well (e.g. water with certain toxins or compounds).