I haven't fed "junk" food to my cats in years. It's expensive with multiple cats and I am far from wealthy, but they are worth it. Ming gets FLUTD attacks if I feed him anything but high quality grain-free food (Wilderness or Wellness). Mac has just been diagnosed with hyperthyroid so cheap cat foods are a big no-no for him. But, if your cats are doing good on them, what's the harm?