16 C.F.R. § 233.5
The practices covered in the provisions set forth above represent the most frequently employed forms of bargain advertising. However, there are many variations which appear from time to time and which are, in the main, controlled by the same general principles. For example, retailers should not advertise a retail price as a "wholesale" price. They should not represent that they are selling at "factory" prices when they are not selling at the prices paid by those purchasing directly from the manufacturer. They should not offer seconds or imperfect or irregular merchandise at a reduced price without disclosing that the higher comparative price refers to the price of the merchandise if perfect. They should not offer an advance sale under circumstances where they do not in good faith expect to increase the price at a later date, or make a "limited" offer which, in fact, is not limited. In all of these situations, as well as in others too numerous to mention, advertisers should make certain that the bargain offer is genuine and truthful. Doing so will serve their own interest as well as that of the public. [Guide V]
16 C.F.R. § 233.5