Of course they drop the rug back off and the cycle continues.
The pros of being in the industry as long as I have and cleaning the volume of rugs that we do is you have pretty much seen it all. The cons of being in the industry as long as I have and cleaning the volume of rugs we do is I have heard it all.
The advice people were offering from what I saw was pretty spot on, including the refund and/or replacement. You can spend your time and energy trying to correct an issue but sometimes it's better to just cut your losses. Every job is different and every customer is different.
And if it comes to going to court, no way a judge sides with the cleaner. How can the cleaner prove they used the correct chemicals at the correct dilution rate? Or that something else that was done caused the problem. The burden of proof then falls on the cleaner to prove the rug is somehow defective and good luck trying to prove that.