Another example is the yellow in cheddar cheese. Apparently the yellow-ish color was originally a mark of high-quality milk from grass-fed Jersey and Guernsey

Another example is the yellow in cheddar cheese. Apparently the yellow-ish color was originally a mark of high-quality milk from grass-fed Jersey and Guernsey cow. Now they use annatto and other spices/dyes to add color to the cheese. Essentially, when the consumer doesn't have complete information they will have to make purchasing decisions based on proxy information. As you note, this can lead trickery from the person selling the product.