Some of Diamond's formulas contain by-products and what-not and I would not feed them to my dogs, but one of their formulas (I believe it's the lamb and rice? Please correct me if I'm wrong) is actually really very good. And I disagree with Nutro being "low-quality" too. The two brands definitely aren't the best you can feed and definitely aren't up there with brands such as Innova or Canidae, but for the lower bracket price-range they're much better than other brands such as Science Diet or IAMS. I would classify them moreso... on the lower end of the high-quality scale. Nature's Recipe I had never thought to be a "low-quality" food, but I've never looked into that brand to know (it was a bit too pricey for me at the time when compared to Nutro).

But bottom line we must remember that we need to feed what works for us and for our pets. If a food works for you and your pet is happy and healthy on it, then don't worry about it. If you're interested in learning more about nutrition and which foods are better, then educate yourself, do your own research, form your own opinions and then decide which is best for you and your pets. Because in my honest opinion the only "bad" food is no food at all