I agree, they should be reported. Unfortunately, I have no Facebook and no interest in obtaining one either.
I must say that the titles for all of these groups are both obnoxiously offensive and cringe-worthy when it comes to spelling and grammar.
Enough is said when one looks at the kind of material which is posted in these groups' pages and the kind of people who join these groups [non-English speaking MJ fans excluded]. One of them even called him a rapist--something which was never brought forth by the Sneddon camp as rape actually requires physical proof of penetration,etc. The fact that these groups exist and that over five people associate themselves with them really speaks volumes of the profoundness of human stupidity.
I hate to say it, but, even if you -do- report them, similarly-named groups will crop up elsewhere and so on, as there's always going to be scum-magnet groups on Facebook, etc.
While I agree that such terribly disgusting groups should not be permitted to exist, I also have to point out that there is nothing which explicitly says they are not permitted to. One of the downsides of "free speech" is the fact that the idiots, too, get to exercise this right. v_v
You might be able to do something about the rapist/molester groups, as what they are doing is technically defamation. The FBI reports disprove the allegations altogether [the only defense against defamation is truth] so they have no foundation upon which to support their allegations. The jury also found him innocent in '05 so that can be used to support our case.
As for the "I hate Michael Jackson" or "I don't care if he died" groups, there's nothing you can do about those. They're not defaming him at all by saying they don't like him--that's just their opinion. A rather poor opinion, but an opinion all the same. The only way you can "get" them is if they're trying to pass misinformation or downright lies as truth in a malicious manner, thus defaming the character of the accused.
Hope I was able to be of help.