Peeing on Plastic

Nearly twenty years ago, I tried using plastic liners for my litter boxes. It seemed like it might be a good idea, and there were times when I could actually pick if up at the edges and dispose of it. More often though, they would have clawed through the bottom, pulled to corners in, and mixed the whole mess together in with the litter.

The worst part of it all was that I apparently trained my cats to pee on plastic. While I had no problems with that before, ever since then, the only two cats that I still have now, that I had then, will pee on any plastic that is left on the floor. And to them, a glossy magazine cover counts as plastic, I think.

They are sisters from the same litter. One of them is known for behavioral problems from time to time but her sister would never make a mess outside of the litter box, unless it's on plastic, and she never did that before the litter box liner experiment.

Kfander, I think they are telling you that it is time to swith over to an e-reader ! (just kidding)
Actually, it seems that you have done an excellent job of training your cats.
Most cats would not want to use the bathroom on something that they can't at least try to scrape and cover up.
Possibly, you can untrain them, though. It might take some experimenting; but if you leave some plastic and spray a dab of vinegar on it, they will sniff it and decide that this is no longer an acceptable bathroom spot.
Of course, you don't want to have to spray your Organic Gardening (or Playboy?) , so you need to keep the shiny-covered magazines put away while you are re-educating the girls.

Vinegar is good because it has a strong smell, but is not harmful if it gets on their feet, and they lick it off. But if that doesn't discourage them; you might have to try for a different substance they don't like. Maybe a little cayenne pepper would work.
One sniff, and they will not like that at all ! !

I have never heard of a cat going on plastic items before. That is a hoot! Sorry, if I am not supposed to laugh at it though. It did remind me of my old cat, Matthew. Anytime my son would come home with his sweaty workout bag from Tae Kwon Do, we would have to quickly wash the clothing and put the bag up high. If not, Matthew would spray his scent all over the clothes and bag. It was not easy to get that smell out of a heavy-duty gym bag!