I.e. - putting cheap, randomly sourced meat into a product - horsemeat etc. Less seriously but also annoying - reducing the size of a chocolate bar/changing the ingredients and imagining we won't notice, or calling it it "New and Improved". Which nearly always means "We've found a new way to scam you by cutting costs and get more lovely profits for our shareholders". Going for cheaper manufacturing and materials resulting in a reduction in quality while still charging the same (expensive) price - looking at you, M&S, for the last 20 years.
Not a new thing, the food industry was doing this in Victorian times. Too much to ask?