Well yeah, platinum blonde never looks natural but that's kinda the point ya? Like when you die you hair an "unnatural" color (bright red or green). I did that once - my whole head was electric blue, and my hair was about down to my back. Ah, the good ol' days.
I dunno, with my own personal style I just go with what I like, crazy or not. And if people mistake me for a stereotype, well, too bad! They don't really KNOW me anyway so it doesn't bother me. But, a lot depends on your job etc in terms of how it will affect being taken seriously and whatnot. It can pose a problem in that sense.