View source for You know you are a crank when...

Cranks, scam artists and fringe theorists share a set of common traits in their writing.  Free-energy nuts are the worst.  Look out for the following signs:

# Claiming not only to having zero scientific training - but also claiming that this is a good thing.
# "They are out to get me/suppress my technology."  Murder threats - claims of being offered a gazillion dollars by "big oil companies" - typically to suppress technology that's already been patented. (When you patent something, you describe fully how it works and put that description up where anyone with an Internet connection can read it...it's kinda hard to suppress it after that!)
# "This is only a demo. I can't show you the much better one I have behind the curtain over here"...yeah...great.
# Over-specific claims. He could make himself rich and famous, fix global warming, solve world hunger and get at least one 
Nobel prize just by demonstrating an actual working over-unity power source. But instead they '''ALWAYS''' have to make it drive a car.
# Claims that being awarded a US patent is actually some kind of proof that the machine works as advertised are always a mainstay of this kind of nut-job. In truth, patents are very easy to get.  Yet somehow they add a lot of respectibility to ridiculous devices. The average patent claim gets something like 10 minutes of a patent officer's time - including the time to read the claim and fill out the paperwork...and that's an average - so most get a lot less.
# Excessive precision in any numerical claims. (eg it's not enough to produce 20 times more energy than you use - it's more likely to be 21.415 times more).