Are there any tips for whitening without commerial whitening shampoos? I bought a bottle of the blue whitening shampoo for like $20 this summer, never opened it, and now can't find it. Ebony is filty and yellow and since it's in the upper 70's today I'd like to seize the opportunity to clean her up a little. Anything I can use without buying another bottle of that stuff? (I KNOW it's going to turn up eventually!) Also, she's got a mark on her butt from the trailer. Not really oily, but it won't brush out either. Any ideas?