Vanished spectators don't properly maintain their vanished state when a player logs out and logs back in. Visible spectators are at best an annoyance and at worst a distraction and a game breaker.

I think this is because when a player relogs, he becomes a new instance of the Player class. Just hide all spectators for that player "onLogin".

I call the method setupSpectators (source) everytime someone logs in or out, I thought. I need to spend a bit of time working harder on it.