The professional real estate community appears split on whether it's a good idea to hold open a house for sale; although, I don't really understand the negative thoughts. It doesn't make sense to blatantly announce that no house should ever be held open, yet agents say it. Why would an agent want to restrict market exposure for a listing?
Common sense says it's smart to expose your home to the largest number of buyers, and getting buyers inside to preview a home is a huge hurdle to jump. It's like keeping the house for sale a secret and saying, "Sshh, let's not tell anybody about this house or invite them over to see it because it just might sell!"
A side benefit for an agent to hold open a listing is the real estate agent might receive buyer leads just from being in the right place at the right time. Yet some agents have actually said, "Well, that open house sold my listing, so I better not do that again!" The successful real estate agents I know report that at least 20% of their sales, or one in five homes, sell through an open house.