Simple answer. Tell her your standards are obviously not as low as hers. You clean, not just appear to clean. When you are finished, the premises are CLEAN. Apperance is not everything, b*****y hell even Liz Taylor is getting married again. What's that got to do with cleaning I here you ask?
Not a lot, but then if she can get married, looking like that, at her age then there's hope for all of us!
Back to the point in hand.
You can please some of the customers all of the time, and all of the customers some of the time, but never all of the customers all of the time. Do not, never try, refrain, from trying to be all things to all people. You get very tired and basically disappear up a very dark bodily orifice.
Give up on her. She is probably costing you more in stress and trying to satisfy her demands than the contract is worth.