Another factor to consider is that some buyers—who may be on the fence about moving, or who aren't considering moving at all—take the leap after seeing an exceptional property at a Sunday open house.

Recently a $2 million property in the Oakland Hills in Northern California sold to a buyer who wasn't in the market for a home. If the listing had not been held open to the public, this sale probably wouldn't have occurred. Another two million dollar listing in Piedmont sold a year or so ago to buyers who walked into an open house. They weren't working with an agent, so they might never have seen the property had it not been held open.

You might think that these are the rare exceptions. But it's actually quite common for buyers to purchase a home they see at an open house, particularly when the market is active and there are more buyers than sellers. In this sort of market, buyers are usually out in force, canvassing open houses, searching for new listings.

There are certainly good reasons not to have an open house. If you have a house full of irreplaceable valuables, you might want to forego a public open house. Even though this may mean losing a buyer or two, this might be a reasonable trade-off for your peace of mind. If you're in favor of open houses, but have security concerns, ask your agent to bring a colleague to provide extra supervision.

Some buyers like to casually preview a property at an open house before taking it more seriously. This is particularly the case with a listing that has a defect, or one that isn't precisely what the buyers say they are looking for. For example, some buyers won't make an appointment to look at a listing that's on a busy street or up a lot of stairs. But, if open, buyers who wouldn't commit to making an appointment will often stop by to take a look. Some buyers are surprised to find they actually like a listing they thought wasn't worth considering.

Good houses that lack "curb appeal" are prime candidates for Sunday open houses. There are buyers who won't even consider a house that doesn't look smashing from the street. But, again, there's a chance they'll take a look inside if it's easy to drop by on a Sunday afternoon.

A common complaint is that neighbors who are just curious will come through an open house. This is not necessarily a bad thing. Neighbors often know people who want to move into the neighborhood.

THE CLOSING: Open houses do potentially benefit real estate agents. But there is an element of serendipity involved in the home sale business that you might miss out on if your listing is shown only by appointment.

Dian Hymer is author of "House Hunting, The Take-Along Workbook for Home Buyers" and "Starting Out, The Complete Home Buyer's Guide," Chronicle Books.

Copyright 2004 Dian Hymer