The phrase "questionable ingredients" refers to substances or components used in a product that may raise doubts or concerns about their quality, safety, or appropriateness for consumption or use. Full definition
There are also a number of questionable ingredients such as inexpensive fillers and low - quality supplements which may do more harm for your dog than good. (dogfoodinsider.com)
Fact is that even highly promoted brand name dog food, brands everyone knows, contain corn and a mess of other questionable ingredients. (feedingmydogbreed.com)
This is not the time to be using products with questionable ingredients, fillers and other additives. (realfoodwholehealth.com)