I'm amazed at the number of times I've been asked by whoever is "supervising" me on a commercial clean whether they need to sign something.
I presume they mean a form to confirm the cleaning has been completed.
I've certainly never bothered with this. It's a bit like that other recent thread about ISO9000, it just seems to create more needless paperwork. And besides, I've always taken the view that the client will pay me irrespective of whether I've had the cleaning signed off. And mores to the point, they won't pay me if they are not happy with the work, irrespective of whether the "supervisor" has signed to say you've completed the cleaning.
Rog