Because they're just too creepy to be real.
Yet, I'd love to see them in 'fiction~ And my favorite still stands as gregomulcia. *snort laugh*
Amomaxia - sex in a parked car (been done many, many times)
Carpophilia - sexual arousal from feeding another fruit (what I'm sure DoA: Beach Volleyball fanboys were suffering from with the strawberry =P)
Coitobalnism - sex in a hot tub (been done)
Gregomulcia - sexual arousal from being fondled in a crowd (*halo* I like writing a challange)
Hebephilia - Adult male attraction to teenage boys; it can also be general adult to general teenager (...so that's what they call Seishirou and Eiri)
Hygrophilia - sexual arousal from tears, sweat, saliva, etc (been done, if the amounts of doujinshi have anything to say)
Nanophilia - attraction to short people (mmmm, short~ X3 If you know me at all, you know what I'm getting at)
Odaxelagnia - sexual arousal from being bitten
Ochulophile - sexual arousal by biting another (for the vampire fanatics)
Phobophilia - sexual arousal by fear (always good for the sadists)
Psycholagny - orgasm obtained by psychic/mental stimulation (yes! I like it! *dances*)
Sacrofricosis - the practice of putting a hole in your pants' pocket to masturbate, most likely in public places (I just found this one interesting, if not slightly creepy and stalkerish)
Somnophilia - sexual arousal by sleeping people (options for molesting, I tell you!)
Symphorophilia - sexual arousal from planning or causing a public disaster (perfect for world conquering types who get off on their demolition work)
:3 Nyao~