We've washed a few rag rugs, check for color fastness and thread strength.
We get all kinds, home made, professional, had one made with her fathers ties (we drycleaned), we also had one that the mother had made of jean material from the time the daughter was a child to adult hood. (HWE hand tool).
They seem to be getting more popular, many we HWE flat, flip and do the other side as we do braided rugs.