Defining obscenity really can't be done. It is based on community standards.(?) You could always go with that stupid cambria list. But, it does look a little boring and just a touch racist.
"On Jan. 18, 2001, Adult Video News reported on the so-called "Cambria List." Paul Cambria, a longtime attorney for the porn industry, was involved in the list's preparation. The list is controversial within the industry and interpretations differ on how it was meant to be applied. Some in the industry say it represents guidelines for the box-covers of adult videos, not for the sex acts they depict. Nevertheless, there is wide agreement that the Cambria List shows how the adult industry is seeking to be more careful, fearing a potential crackdown on pornography by the Bush administration."
No shots with appearance of pain or degradation
No facials (bodyshots are OK if shot is not nasty)
No bukakke
No spitting or saliva mouth to mouth
No food used as sex object
No peeing unless in a natural setting, e.g., field, roadside
No coffins
No blindfolds
No wax dripping
No two dicks in/near one mouth
No shot of stretching pussy
No fisting
No squirting
No bondage-type toys or gear unless very light
No girls sharing same dildo (in mouth or pussy)
Toys are OK if shot is not nasty
No hands from 2 different people fingering same girl
No male/male penetration
No transsexuals
No bi-sex
No degrading dialogue, e.g., "Suck this cock, bitch" while slapping her face with a penis
No menstruation topics
No incest topics
No forced sex, rape themes, etc.
No black men-white women themes