We use these as food dispensers for our dogs. They love rolling it around to get the food out and rarely eat from their food bowl anymore. I had read that dogs enjoy finding their own food and apparently this works for ours. We've had these for a few years and they are just like new. We just had to make sure we got a small size so the dog food wouldn't roll out too fast.
This is a wonderful interactive toy for the thinking dog. Not all dogs will like it, but our Rottweiler does.
The only problem we have with it is that even when we fill it with doggies treats, he empties it quickly and wants more, more, more. But during the time it is filled, it keeps him busy as he chases it about the house rolling it, picking it up and dropping it until it is empty. It's also a great toy for outside as it bounces all over the place and our dog just loves that. He takes it outside on his own and we play fetch with it. This is definitely a great toy for active dogs.
As for cleaning it, I've had no issues. I simply put it in a pan of soapy water to soak and rinse it really well by soaking it in clean water, then rinsing it out a few times and let it air dry. A quick rinse through with hot water in/out in between also suffices.
I've bought most of the different types of Kong at one point or anything and the ball seems to be the favorite for my husky and collie/GSD mix. Its easier to stuff the balls with larger treats (harder to remove) to keep them busy longer than the regular kongs, plus they roll them around to play with them. The ridges on the side are also great for peanut butter, squeeze cheese, or the kong stuff'n stuff. Given one of the kong balls that we have vs the regular kongs, my dogs always opt for the ball first, so its definitely a keeper!