If its really bad with lots of dried blood & mud & misc I take the bag off the frame IF its only a few places that are bad leave it on & spot clean it . I mix some scent killer laundry detergent with some Super Purple or similar product in a spray bottle or bucket, wash & scrub the bad spots really good rinse with a high pressure hose or pressure washer . Hang up somewhere where you can put a high output fan on it .After its dry I always spray the bag down with a scent killer spray & hit it again with the fan !! Finish the bag off with a couple of hand fulls of fresh sage brush Juniper or pine needles let it set for a few days !!!!