Scientists Are Not Created Equal
This is one argument that sometimes trips me up: "But Dr So-and-so, a noted scientist says..."
My usual response is that either the person I'm arguing with is lying, or that the person who claims to be a scientist is lying about being one.
I tend to give special dispensation to people who really are scientists, and I often forget that scientists are just as prone to crazy or stupid as anyone else.
Take a read (or a listen)... this guy articulates that very well.