Gregory Mankiw is a professor of economics at Harvard and he's listed some of the myths relating to the economy that one hears a lot, especially in election years.
The sad thing (of course) is that some of these will never ever be disbelieved by those who want to believe them — like the one about how cutting taxes, especially for the rich, is a guaranteed way to stimulate the economy. No matter how many times it's tried and doesn't work, some people will insist it just has to be tried again — and again and again and again. Remember the definition of insanity? Doing the same thing over and over and expecting different results.