I'm glad their stool tests came back negative! When Cassie starts to smell more like her bottom than her usual kitty self, I try to give her a quick rubdown with a Kitty Wipe, which I bought at Petsmart. They're disposable, pre-moistened, have a clean smell and contain aloe. I also try to do it when she's flaking (cat dandruff) a lot. She, of course, hates this. My neighbor just wipes down her Persians with a damp washcloth from neck to tail.