I also know of the kind of kitty you speak. Jordie, an orange boy, just won't be adopted because he has peeing issues. They are now trying Prozac on him. The rescue is keeping their fingers crossed that it works. Jordie is a sweet boy that needs to be away from the TONS of other cat smells in his foster home. I've tried to convince them to please switch him with another cat in a no other cat foster home. Unfortunately, the woman fostering him won't give the other cat up to the rescue and they're not pushing it. I go over there to keep Jordie company. I try (it breaks my heart to see him in this situation) to give him one on one contact, talking to him gently and petting him. I feel so sorry for him.

If the kitty you speak of sounds like Jordie, then maybe you need to find a no other pets foster home for him and allow prospective adopters to see him in his own environment.

I wish you luck.