I get phone calls from people who believe that they are entitled to see a house just because it has a sign out front. Not so. Where it is true that the yard sign is a Commercial Invitation, I have a professional obligation to screen people who I bring to the property and take inside. They have to be a qualified buyer. When I unlock that door, I am basically telling the listing agent and owner that I have done my Due Diligence in determining that the person who is with me is actually a potential buyer.
Sometimes people who want to see a house get fairly ugly when they are told they can't do it the way they want to do it. For an interesting blog on people who think the best way to buy a house is to deal directly with the listing agent, go see http://actvra.in/bWJ
In the last week, I have dealt with phone calls from two people who became angry because I wasn't willing to drop everything and go unlock a house for them to see, no questions asked. In both cases, the callers told me that they were only interested in seeing that house and that house only. That statement almost always sets off the Tilt Meter. That statement is usually code for some other agenda.
For example, I have gotten phone calls from people who lived in the house as a child and want to see inside. A more common example is that they are neighbors thinking about selling their own home and they want to see how their home compares.
Get yourself a Buyer's Agent, people! You just have no idea how much better your deal will go if you take the time to find a competent Buyer's Agent.....
If you aren't a buyer, the very best way to get into the house is to contract the listing agent and ask when there will be an Open House. You are completely welcomed to just come and look at an Open House. Usually 1/3rd to 1/2 of the people who come through the door at an Open House are not buyers. And, they are just as welcomed as people who are well on their way toward the closing table.