I agree that having an abnormal attraction does not indicate an obsession, it is how much your behavior is influenced by the attraction that determines whether it is an obsession or not. To find the idea of peeing on someone arousing in passing is completely different from actually pursuing the act in anyway that is not completely convenient: drawing crude images of the subject when you have limited artistic ability, collecting images of the act like trophies, or even making an effort to find someone with the same desire. Something so trivial and so typically considered unpleasant should not hold enough significance for you to make such an effort towards obtaining it. If peeing on someone for fun matters to you either way, then it's a fixation.
The popular quote "Beauty is in the eye of the beholder" is misused more often than not. Many people interpret it to mean that anything can be considered beautiful if someone thinks it is so, but most experts in the field of aesthetics will tell you that it actually means beauty does not exist without an eye to behold it, and that beauty is actually easily defined by a handful of pretty exact principles. The rule of thirds, for example, is not subjective. It has been determined by science that the subject of a composition should take up roughly one third of the entire image to most effectively activate the orbitofrontal cortex, which is the part of the brain that reacts to beauty.
Other concepts used to measure beauty are form, function, complimentary elements, symmetry, and complexity. Our standards of beauty are pretty consistent with these measurements as a whole. I believe anthros are biologically favorable, and that is what makes them attractive, not a mindless desire to bone a freak. I believe I cannot be aroused by anything that wouldn't make absolute sense to any rational person, and that if I couldn't make sense of it, I would instantly be incapable of being aroused by it. I believe fetishes exist out of emotional immaturity, and the inability to control one's impulses. Impulses are what we grow out of when we become adults, so I believe fetishists are somewhat mentally defective.