Hey guys!
I was just browsing through the hamster Wiki a bit, and stumbled upon this:
Hamster Roll Around / Zoomer Balls - Good or Bad? - Hamster Central WIKI
I was honestly very shocked, it says hamster balls can be a 'great toy for your hamster if used correctly/carefully', despite all the big negative things that can happen to hamsters in there, some of which were listed there too! I see hamster balls as absolutely terrible, and don't see how people could use them.
That being said, I would really be interested to hear your opinions!