I'm in such a place where we have a suite-only restroom, accessible only to staff. I'm also unfortunately in a place where I have had to fish unflushed paper towels out of the toilet, put there by an unspecified person who is apparently accustomed to flushing all manner of materials down their home toilets.
I was happy to take the bullet (or the coathanger, as it were) the first time this happened. But since then, staff meetings have been held and e-mails were sent updating the gathered on the inadvisability of such things. Everybody onboard, it would seem, and in agreement.
So when it happens again, I think you have to say we're no longer operating under the rules of a civilized society.