1. No one under 18
2. No bloodletting
3. No forced sex that is not consensual role play
4. No animals
5. No scat

I think these are the minimal requirements.
Most porn I see is either vanilla boring, par for the course, or sticky gooey and messy to me but this is a business so sell 'em what they want to see -- my personal tastes do not determine my product offered.

How many car salesman will only sell you a metallic grey automobile?