With Private Clubs the good thing is only Members that have accepted an Invitation are the only ones that can see the Club. It's not visible to anyone else except those who accepted an Invitation. So there's no chance of anyone clicking and inviting themselves.The same in PM's once a PM Group has started the only ones that can see it are the one's that have been added to the PM Group. The only thing there is there is no ability to remove anyone. If a Member becomes disruptive the only thing is begin another PM Group and Exclude who you don't want. In Clubs I am not 100% Certain but I believe whoever starts the Club Privately has the ability to kick anyone they want out they no longer want them in that Group.