Public bathrooms, especially inside the stalls, should be adequately lighted so that users are able to clearly see all areas of the toilet, making it easier to inspect and take measures to clean or otherwise prepare it for their use. Being able to clearly see all aspects of a well-lit toilet will clearly have beneficial sanitary consequences, reducing the risk of disease transmission. Perhaps a minimum of 250 lux of light should be the minimum standard. Public bathrooms in parks or campsites where it is not practical to install such systems (due to lack of electrical infrastructures, etc.) should probably be exempt from this requirement, however, they must design such spaces to allow for maximum natural lighting.
Public bathrooms should have music or some kinds of sounds being played so that it could mask unwanted, uncomfortable normal bodily noises that often cause embarrassment for the users. Park and campsite bathrooms may be exempted from these suggestions due to lack of electrical infrastructures, etc.
Some suggestions would be to play informative/educational sound clips (news broadcasts, TED talks, etc.) so that the time is not not uselessly wasted on music, landscape sounds or other non-productive sounds, although these sounds would be much better than nothing. Another example: churches could have preaching or singing broadcast into the bathrooms, especially during their worship services, so users won’t miss that part of the service.