My favorite quote of all time is "The cure for ignorance is education; the cure for stupidity is death." The only test I've successfully used to determine which I was dealing with is to ask a question that the established dogma hasn't really covered and actually requires them to think on their own. My experience with resistance has been mostly male but the questions would work equally well being asked of a female. Ask of a group of men have you ever tried on a a pair of your wife or girlfriends panties? Some will admit to it, some will not. If you can get one to admit it ask them if they suddenly develop an interest in men when they put them on? The usual answer is an emphatic denial of any male interest. The follow on question is then how many articles of womens clothing can you put on before you become gay. (Mind you I know it has nothing to do with it one way or the other.)
As an alternate you can use the classic woman who sleeps in his boxers and t-shirt or puts said items on after sex. Does she instantly upon wearing these items fancy women instead of the man she borrowed them from? Does she like girls when wearing pants and boy when wearing skirts or dresses?
The goal is to get a thought provoking question into the brain before they see the challenge to their beliefs and raise the dogma shield to full power.