When I was watching a Disney movie I found out that I think the Disney Princesses turn me on.
Are you joking? What turns you on about Disney Princesses?
They have an aura of purity around them.
It's okay to be attracted to the characteristics of characters. People have different fetishes in life and as long as no one is being hurt, that is okay.
I'm posting porn on princesses' tumblrs.
You're free to have this fetish, as it doesn't really hurt anyone, but posting porn to random tumblr's that don't share your fetish is wrong. Do you think you would be happy if someone posted porn that you're not into to your tumblr?