A very good post by Dr. Kurt Harris.
The key is you have to be skeptical, and thoughtful. Try not to just jump to conclusions.
When I discovered my wheat sensitivity, I was actually testing something else (vegetable oils). I actually thought the whole gluten-free thing was kind of bogus...
But I'd inadvertently changed two variables in my diet. When I stopped eating veggie oils, I also lost my cravings for carbs. Which meant I didn't eat any wheat, by dumb luck, for a week. It was a happy accident.
And as Dr. Harris suggested, I went to my Doctor and had him run thorough blood work, so that I could confirm that I wasn't killing myself with this caveman diet.