Try a slogan like "democracy is retarded" on the other hand and you'll have butchered the holy cow of practically everyone.

Sure, but that's because slogans aren't about convincing people; they're about signaling group affiliation. Wear a T-shirt with "democracy is retarded" on it and you're effectively saying that you belong to a group that no one has ever heard of and is apparently openly opposed to one of the major shared tenets of practically every active political faction out there. Not a good way to win friends.

On the other hand, I'd be willing to bet that writing a series of blog posts, or even a book, on why democracy is retarded (ideally not in those words) wouldn't paint you as anything more than, at worst, mildly crankish. Very little is actually unthinkable in the educated world -- but if you're going to voice opinions outside the Overton window you'd better voice them in terms of actual arguments. By definition, you can't expect your audience to be familiar with the existing arguments for them.