This information is from the Bonita Springs City Website:
A Green TAG placed on a structure is for first responders. It allows them to track structures they have searched. Green tags are not intended to provide safety information to the general public.
A RED TAG placed on a structure means the house/structure was found to be in hazardous condition. It has been determined to be uninhabitable in its current condition. While this does not necessarily mean the structure has been condemned or is structurally unsound, property owners entering structures with a red tag are doing so at their own risk and should use extreme caution.