People will look for any reason to be nasty to someone they don't like, and of course it is VERY easy to be nasty about Michael. I have found the best way to stand up for Michael is to not say 'I am a fan' and to have a slight unbiased way about the way you explain things, i.e. instead of saying 'he IS innocent' say 'I can say he's innocent about as much as you can say he's guilty, but I can only go by the evidence found against him, which is nothing. Until the day he is PROVEN guilty he will be regarded as innocent to me because I chose to judge someone based on proof not presumption'. If you keep it like that then you are less likely to be attacked, or at least the attack won't be as harsh as if you were all 'I love Michael I know he's innocent, he IS innocent, he sang all these songs about saving the planet and the children', etc. If your emotional connection to Michael isn't so apparent then they aren't going to attept to hit a nerve to upset you as much as they would with an obvious fan.
I hope that makes some sort of sense...