When I went to real estate school I learned about the "hogger." That is the sweet deal that our instructors told us would happen if we represented both the buyer and the seller. Stories were told about unrepresented buyers calling listing agents and those agents selling the listing to the buyer. It is also called dual agency.
Agency is an issue I think about often and every six months or so I write a consumer-oriented post about it on my blog. I keep the Minnesota agency disclosure in each of my listings so that I have it on hand at all times if I need to show the listing to a buyer.