Hiring an advertising agency has both advantages and disadvantages: Advantages include the agency's expertise in marketing, their team approach which leads to fresh ideas, and the time savings for the business owner who can focus on other operations. Disadvantages include the costs of the agency's services, that the agency may not know the business as well as the owner, and lack of clear communication from the owner could lead to misunderstandings. Overall, business owners need to carefully consider their needs and provide clear requirements when hiring an ad agency.