Amongst marketing management, there is a pretty broad division about the cost-effectiveness of using celebrities. Some people are really on it, and some are really off. It depends on the celebrity used and the product they are endorsing.
When a marketing manager has to select the right person for the advertisement, they have a lot of factors they need to take into account, because that person is now representing the brands image. For example, if Nike hires a sports star that is on top of their game, and dominating other players, it gives Nike an image of being better than other brands. But if Nike gets someone who is arrested the next day for drug abuse for example, it doesn't make Nikes image seem respectable. The endorser needs to select famous people, who have similar life styles to the brand image that is to be portrayed. .
The consumers are much smarter than advertising agencies give them credit to be. Consumers know that they will not become better people over night, for consuming a certain type of product. This is why some marketing advertisers put off high paid celebrities in their commercials. To them it's not worth paying the hundreds of thousands of dollars to endorse a celebrity for a small percentage increase in sales or brand recognition. .
On the other hand, some products are "made" because of the right representative. Having a celebrity endorse a product, when they are in their prime, can be one of the best moves made by an advertising agency. Not only does the company gain from their advertisements, but also when the celebrity is getting other free publicity for being popular. People recognize the celebrity as being part of your brand, and link your brand with their names in other advertisements. .
Marketing managers have to determine which celebrity would be most effective for representing their product. Using someone like Elvis for a pizza brand would not be the most effective advertising.