My opinion is that parasites would not thrive on a shower floor, because it would not be a source of food for them. Typically they live in the host where they can survive like in the body of animals. Worm parasites are passed on this way, whereas protozoa parasites find their habitat in untreated water.
Acne is typically caused by bacteria. Go to Beyond Wellness dot com and look at their tongue diagnosis page and repost what the website said.