Increased focus: In a clean working environment, you are less likely to be distracted by cluttered objects, and that greater level of concentration leads to more and better work being done.
Less time wasted: A lot of time can be squandered when searching for documents in a messy workspace. In cleaner, well-organised offices, paperwork can be tracked down easily and quickly.
Less stress: A cluttered desk can result in you trying to focus on too many things at once, which lowers your stress threshold.
Greater profitability: Instead of wasting time looking for documents, workers in a clean office get more work done, which helps with profitability in the long-term.