In Washington state, Brokers can represent either the Buyer or Seller exclusively in a transaction, or act as a "Dual Agent" representing both sides. Dual Agency can work out sometimes, but most often it's not in the best interests of either party because in the eyes of the law, both Buyer and Seller become "Customers" rather than "Clients". That reduces the Brokers fiduciary responsibilities, sometimes leading to charges of favoritism, or conflict of interest. (Written approval from both Buyer and Seller is required to proceed.)
Well-informed Buyers and Sellers spend the necessary time and effort to choose a Broker they believe understands their wants and needs, who has the skill sets, and will do what it takes to see them through.