@Growler, up until these two, I'd always been lucky too - like I said, I just thought they were born that way!
When I find the spots or areas, I'm cleaning them with this stuff called Scat cleaner - I'm thinking I could do better though. It doesn't seem to do a very good job. And the vents are a problem! How the heck do I clean inside the vent?
@SCM, there is at least one cat condo in each large room - so one in the living room, one in the great room, one in my bedroom, and one in my friend's bedroom (we are suckers for kitty condos - we love watching them play on them). A couple of them are only three stories high but the other two are very high with a lot of different shelves (our tallest has six different levels). They all also have little built in "houses" where the kitties who like enclosed spaces can go.
Funnily enough, now that you mention it, the kitty condos attract four of the cats heavily. The others rarely or not at all. The two problem children, for instance, don't seem interested. I very occasionally see Honey on it but not much.
The thing is that there's NO question that Honey would like to be an only cat. We always got along ok before my friend moved in but she's always been a bit titchy with the other cats. Nothing extreme but she would be very happy if she and I were the only living creatures in the house - she won't even let the other humans who live here pet her very often. Pumpkin doesn't mind other animals at all (even the dog doesn't bother him) but he's afraid of the other people aside from me.