Interesting no one has mentioned the double dip regarding agency relationships. The reason broker/agents are not inclined to disclose who is working for whom centers on the commission factor.
By example: If I represent the seller (seller's agent) I am advertising the property. Hopefully my skillful marketing brings a buyer. The potential buyer calls ME (the seller's agent) to see the property. I show MY listing, the potential buyer likes MY property. The potential buyer signs a purchase offer.