But the really annoying bit will be that if you go back in 6 months the paper will still be on the wall! She's not happy until it's free, when all of a sudden she can live with the mark.
What we do when we do insurance work, or any other work come to think about it is. We all carry a digital camera with us and we take pictures of before and afterwards. That way there is no complaint. Since we started doing this we don't have any complaints against us.
We were sent round via an insurance company to remove a bath to have the floor remove, when the camera was pulled out the customer asked what we were doing. I explained that we always take pictures before and afterwards. Her reply was, 'oh thats a shame, i was going to claim a new bath from the insurance.'
Once back at the office, all the pictures are down load to be kept on file unitl needed. (if at all)
always took a camera when investigating complaints, when asked why I wolud explain it was to document damage, customers would quite often say " shame was hoping gas company would pay for carpet, redeorate etc etc. Half time never had any film in camera, it was before digital days.
WHY Would the customer deface the job? If the customer wasn't happy, or the OP didn't do the job, a bit of 50/50..Take it to the Trading standards, or small claims court. I know that both are known to swing the lead a bit.