A. They get banned ten times or more and STILL come back to FR!
Other clues are those who exhibit the characterisitics of Truculent Evolution Denier syndrome (TED). TED is manifested by obsessive/compulsive behavior, such as signing up on FR under new names after having been banned for ignoring the owner's request to not spam threads with the same old moronic screeds when a link would have sufficed.
Additionally, TED, sufferers tend to be fixated on certain topics and are drawn to repetitious behavior, such as posting obnoxious anti-evo cartoons, posting psuedo-witty put-downs when they have no substantive rebuttal, being fascinated by all things Balkan, flinging anti-smoking and anti-SUV invective, and a tendency to show off their knowledge about bows & arrows and firearms. Other indicators of TED are preoccupation with Velikovskian nitwittery, Faces on Mars, Saturn hovering over the North Pole "reducing the felt effect of gravity," Halton Arp's long since discreditted alternative explanantions for Cosmological redshifts, and a child-like worship of the Wistar Symposium of 1966.
Be aware that there is no known cure for TED, but scientists continue to look for one....... hovering over the North pole, carried by a big mean-looking ASCII bat.