As an adult who grew up in country where ball pits simply weren't a thing:

My own ball pit? Hell yeah!

A public ball pit for adults? Depends on the crowd.

A ball pit for children? Haha no, there's no way someone didn't pee their pants in there, or dropped some food or snot.

It's surprising just how much mess a single chocolate bar can create.

I'd say actual junk playgrounds sound more sanitary.