Education and boundaries.
Not telling him he is wrong but educating him about how you feel about such...
Why do you watch them? I think they are disgusting.
I would rather not have such in my house. What would our daughter think if she ever sees you watching such?
Some guy some place is getting rich by taking advantage of others and for me that is good enough reason to not watch such.
Boundaries... as you see fit to place them and able to hold them.
If need be... a child proof locking program on adult content that only you have the password for is one partial solution at keeping such out of your house.
Many times my wife would open my eyes to problems by sharing how she feels about my actions or lack of actions. When you do this or say this...this is how I feel. She wasn't saying I was wrong so I had no need to get defensive...she would say how things made her feel and leave the choices to do something about it in my hands.