For example, ABC brand bread is on sale, XYZ brand bread on the shelf next to it is not. Sneaky Manager puts the sale sign for ABC bread on XYZ's shelf, knowing that most people will see the sale sign and assume XYZ is the one on sale and buy it, even though the sign clearly says ABC is the one on sale. If someone spots the "mistake", he quickly corrects it, but more often than not, no one says anything about it, so the sign stays in the wrong place the whole time the sale is going on.
This is obviously immoral, but is it illegal? If it is illegal, what laws (besides truth in advertising) would Sneaky Manager be breaking?