Choosing a carpet cleaner who doesn't offer a money back guarantee, in my view every carpet cleaning company should be fully accountable for its work. And if you aren't pleased with the job in every way, you shouldn't have to pay for it. Not all carpet cleaners offer a guarantee. Or, if they do, the guarantee may be "limited". Ask the carpet cleaner if he offers a money back guarantee and then make sure the cleaner includes it on his written quotation.