Some time ago I spoke to a friend of mine over the phone and he started talking about a book he was reading about cropcircles. So I tried to tell him in a polite way that I don't believe in the whole conspiracy around that. He just told me to get the book and read it. Afterwards I would think differently about it, he assured me. Well, more to prove him wrong than out of my own interest, I got the book and started reading it. I haven't finished it yet, but I came across a pretty nice example of bad astronomy already.
In the beginning of the book the writer starts describing how the first cropcircles that appeared looked like. They were still very basic shapes, like a single circle or one circle with some more around it. Because the shapes were still simple, some people thought that they were caused by some kind of local tornado. This already sounds stupid, but it gets better. He continues to write that al cropcircles in the northern hemisphere are rotated clockwise. Then he writes that this really makes sence, because the coriolis effect causes winds to rotate clockwise on the northern hemisphere and counterclockwise on the souther hemisphere. Uhm... wrong! It's actually the other way around.
I think that th fact that a whole theory was based on a wrong statement tells something about the credibility of such a study.