Not Dr. Lisa, but Its those little white pebbles right? Well ECID of course, but when our shelter acctually had a cat behavior hotline, many many people that called with litter box avoidance issues and were using that litter/any of the crystal litters had a complete reversal of the problem when they switched to clay litter.
I believe that the urine gets soaked up by the crystals so unless you scoop the discolored ones the cat is stepping on urine soaked crystals.
If you want to try them, leave their regular box down and give them an extra box with the crystals in it. Many cats dont like the way they feel on their feet like the pelletted litter.