Would it be possible to concoct a conspiracy theory so absurd even dedicated conspiracy theorists would reject it as improbable?

I’ve posted links to this video in answer to several questions. I guess it should be no surprise. We live in an age of technology and scientific achievement beyond anything our ancestors could have even imagined possible just 200 years ago. And yet we are in many ways less well educated on average than the citizens of that age.

The 30 second sound bite is now too long for the national attention span, and has given way to the 10 second sound bite. In an age where science is probing the very boundaries of the Big Bang’s Cosmic Microwave Background Radiation looming 47 billion light years away, and looking at subatomic particles doing amazing things in the attometer size range; much of the public’s belief in fairy tales, witches, ghosts and demons is back to what it was in the dark ages.

People who firmly believe that the government is profoundly incompetent and incapable of doing anything right also swear that this same government has been successful in a massive, half-century long coverup of extraterrestrial invaders visiting earth. The credulity level of today’s Americans is appalling.

Given the current Internet environment, how insanely ridiculous would a proposed new conspiracy theory have to be before reasonable skepticism would kick in?