Some years ago when Japanese ceramic rings were touted to wash your clothing without soap, Consumer Reports tested them against leading laundry detergents. They found that people could not tell the difference between the ceramic rings and laundry detergent. They performed the tests again using plain water vs the rings and detergent. No differences. Note that the clothing was washed and dried. Likely the drying process took care of any odors and such.
Have tried myself and it seems to work, although just for ducks I now use tiny amounts of detergent.
