Is sufficiently advanced stupidity indistinguishable from trolling?

[Someone]

OK, serious question here. There have been a few posters lately -- etv78, Urbanredneck(2), etc -- who are just so aggressively stupid that my mind refuses to accept them as real people. Like Patrick Star or Peter Griffin, they're too cartoonishly dumb for me to imagine them functioning in the real world. It's not that I don't think there are people that stupid out there -- but they're just too eloquent in expressing their utter stupidity. I remain convinced that they MUST be trolls, playing a character.

And yet... Others seem to think that these are real people with genuine beliefs. My mind boggles.

So... What do you think? Stupidity, or trolling? Or is sufficiently advanced trolling indistinguishable from stupidity?