I picked up a rug that a customer had cleaned by another company and it is browned out imo. My question is can I use brown-out on wool??
in most cases yes. Test a very small area first Rob and wait for it to dry. Do you have some pics to share?
Often just a pure water rinse and sun drying does the trick. Mild acids are safe to use on wool, but avoid the strong stuff. If it comes down to it, a mild reducing agent will be safer than an oxidizer, but test remedies first to find your cure (if there is one)...