Just a thought on this whole discussion/argument/whatever. Even if MJ is safe for dragons to eat (and we only have anecdotal evidence from other threads & posters), we don't know if it's any good for them nutritionally. Sure, we can feed dragons all kinds of things that don't outwardly seem to harm them, but 1) we don't know if it's good for them in the same sense that iceberg lettuce isn't good for them as a staple. 2) it could have some sub-clinical effect on them that they can hide. We all know how good they are at hiding when they're not well.
My 2 cents is why chance it when we know that there are so many commonly available foods they can eat? It seems irresponsible in the same way as the knuckleheads here in Colorado who drive high (or drunk for that matter). I don't care if someone gets stoned out of their mind every night at home as long as they're not harming others. The line for me is when they drag others into it (other drivers, children, pets, etc.). I'm not saying that's what the OP is suggesting doing, but to anyone who is thinking about it, I'd say if you really care about your beardie, you should think twice before doing anything that could harm them. That includes feeding them foods containing known psychoactive chemical compounds. And, to those with the argument "oh, but it's natural, it's just a plant, etc.", I would counter that fireflies, nightshade, mercury, and arsenic are also 100% natural, but you wouldn't feed those to a beardie either.