There is no standard for "natural" cleaners. There are standards for "green" cleaners. Third party approving organizations in our industry include Green Seal and EPA DfE (Safer Choice). We have a manufacturing standard for products that we make called "Green Balance". We have about 40 products that we make which meet our Green Balance standard, 4 are approved by EPA DfE and 2 are approved by Green Seal.
We need to remember that restoration cleaning which keep carpet, fabrics, etc from being thrown away is a "green" practice no matter what chemical you use. Fluorochemical protectors are not green in their formulation, but when used and applied properly extend the life of the surfaces they protect which again is a "green" practice. Make sure that your focus of "green" is not micro but expands to a macro view recognizing the value of a "green" practice.