This is an old and often deceptive marketing trick: Someone advertises something with a low price, and then the customer goes to buy the product but finds that it’s unavailable. However, since the company has the customer’s information or attention, they will try to sell them something else. This tactic is called “bait and switch” and usually ends with upset buyers. In some cases, this kind of marketing can be considered false marketing and therefore illegal. With SEO, this can sometimes unintentionally happen when a website includes keywords that describe something the website doesn’t have.