Yes, you tell them.

And the answer would be...not too many. And I too wondered the same thing. BUT, I was told by people with a whole lot more experience at placing cats than I have that there are people willing to give them a chance and that quite a few known pee-ers have stopped once they were in a new environment.

I myself, many years ago, took on a cat that was returned to a shelter for litter box problems. And at first he gave me problems. But we worked through them and I had him for 12 years (11 of which were accident free).

Maybe I should have just kept my problems to myself.