How sinful would it be to watch these movies that are rated "O" for Catholics? I like to go to the movies every now and then and I do watch offensive movies, but it doesn't reflect who I am as a person though. How about playing video games that are violent in nature; like the Grand Theft Auto series? Again, I like playing the games, but I know reality from fiction and the games don't give me any ideas if you know what I mean. Bottom line -- I like to play the games just to play them and watch movies just to watch them.
I think we get into trouble when we say "I know what affects me and what doesn't." Psychologically, there are many levels at which we can be influenced.