When does an image cross the line and become offensive? What is the litmus test for public decency standards on Caedes?

We need to define what sort of image or language would be in clear contravention of or noncompliance with established community standards. We need to establish a convention of community standards for this site. We need to define the difference between sensual and sexual in content. What are the acceptable limits? What constitutes offensive, disrespectful or distasteful images or language?