I`ve just put a hammer through the one that I inherited with my hamster Boris as I don`t regard them as a natural thing for a hamster to be in. It`s much better to set up a safe play-pen for them and sit on the floor while the hamster runs around and gets to know you. Puting them in a ball just allows them to crash into things they can`t see. Imagine being in one of these claustraphobic spheres? You don`t know where you are and you don`t know whether your in it because something outside of it is waiting to attack you? maybe they run around in them through fear and not enjoyment, or because they don`t have a choice?
Either way, I`m not a fan of them and usually urge people to look at the better alternative and that`s take the time out to spend with the hamster and socialise with him/her.
My hamster was placed in a ball most of the time and my nephew did say that they hardly handled him, so I suspected this is why he needed to be put in a ball because they would`nt handle him. Not only that but he was kept in a Rotastak Space Command.
Life has changed for Boris now and the ball is where it belongs. Smashed up in the plastic bin for recycling where nobody else can use it.