Cat Attract... Any ideas?

I was in a pet store to buy a bag of kitty litter and overheard someone talking to an employee about litter suggestions. The employee when through all the types they had in stock and when he came to the Cat Attract he looked over at me since he had sold me a bag of it a long time ago. I told the customer that as far as I knew it really does work. All three of my cats gravitated towards it and left the box of Swheat Scoop and World's Best alone. My problem with that brand is that it's clay and not flushable. We started chatting about what the mystery ingredient is that attracts cats and we joked that maybe it's catnip. A lot of cats love catnip, maybe it's mixed into the clay?

We were only kidding around but I started thinking... I wonder if anyone mixes catnip into their kitty litter or has ever tried it? For a moment I considered doing it myself to see what happens, but then I got images in my head of one cat doing a #1 and/or #2 and then another cat rolling around in it afterwards. My girlfriend and I just went through the wonderful fun of bathing all the cats a few weeks ago. I'm not too eager to do it again so soon and I'm pretty sure she feels the same way I know for sure that the cats don't want to do it again... ever!

Anyway... my questions to you... Any idea what makes a cat want to use a box full of Cat Attract over another brand? Anyone ever try mixing in catnip with their regular brand of kitty litter or does it regularly?