5. A previous owner, or one of their relatives Over years of open houses, a busy listing agent will surely run into an old seller, or their children or grand kids who grew up in the home. These people come to the open house to see how it looks and to reminisce. Lots of memories happen in a home, and the opportunity to go back in time can be a real treat.Usually, there’s no harm done. But you might encounter the former seller’s cousin Steve, who tells the listing agent about how the current sellers did a horrible job on their backyard makeover. Even worse, you might get a relative who starts crying on the listing agent's shoulder about her grandmother, a previous owner, who recently died.A good listing agent will let any and all of this roll off their shoulders, keep a professional game face on, and keep their eye on the ball. They solicit feedback from buyers and make notes of their comments, reactions and questions.If you’re attending an open house with no intentions of buying, keep it to yourself. Be as subtle and unobtrusive as possible and don’t waste the listing agent’s time – unless you have some helpful feedback for the agent or seller.