You obviously have not observed or cared for psychiatric patients like I have professionally, or have seen how true fetishes CAN control one. Besides, we are beyond the animal stage. If you believe in evolution, then man is the next step ABOVE them. If you are a creationist or believer in intelligent design, as I am, then Man is way off the scale in comparison to animals. Either way, what arouses you MAY NOT arouse me. And vice versa.
It sounds like something dumb, but honestly, can you say that if you were offered sex, and you gladly obliged (obviously), that in the course of sex that you would not become aroused?!?
Your premise puts the cart before the horse. Is not the arousal required before the sex can occur in most cases? There may be some exceptions (ex. hookers/sex workers for whom it becomes no more than "just another day's work and can become a n emotionless act), but on the whole, if the guys' rod is flaccid, sex ain't happening (assuming your referral to sex is intersourse and not relegated to just a man giving oral sex to a woman). There are some people whose minds are wired such that if you stood (insert prefered male or female sex symbol) in front of them, nothing would happen. But, if you put a perfect representation of the object they have the fetish about front of them (breast, foot, hand, or whatever), then they are more aroused than a fraternity pledge in the midst of his first panty raid.
The cases do exist. The amount of differing styles of porn out there alone are staggering proof of that. Once by mistake, I ended up on a website devoted specitically for guys that got off on hot women driving vehicles stuck or mired in mud and them walking in it trying to get unstuck (can't remember how I got there, looking for parts for my jeep I think and got a bad link, but that's not important). A event that would trigger nothing more than, usually, sympathy to try to get them out of there, but they were SELLING vid clips of this stuff to guys (or gals?) that "got off' on the subject.
Sheesh, just look at the reactions people receive to pics, vid clip and other posts on this site. Do you really need any more evidence???