Buyers need to feel completely at ease when they are looking at a new home to possibly purchase. You being there makes things extremely awkward and uncomfortable for the buyer. They need to be able to fully inspect everything, and they don’t feel comfortable doing so when you are present. They need to ask questions; some of the questions might offend you as the seller. This is why they should be able to ask their realtor questions without feeling uncomfortable. They will want and need to look through all drawers, move furniture to double check that everything is intact. For example, if they move a sofa to be sure no scratches lay underneath on the floors, you will probably be offended. This is just one example. See: Home Selling: Unique Marketing Strategies.
Honestly, you should be glad if you find a buyer that wants to do these things. If a buyer comes to see the home and only glances at it, they probably aren’t very serious about your house. Thus, most buyers aren’t going to do this if you are there. So, you’ll never know how interested someone really is in your house. Better to not be there, and let your realtor update you afterward on how closely they inspected the home.
When the owner is present, it makes the buyer feel like an intruding guest. This is probably the worst feeling you can instill in a buyer. Another reason you shouldn’t be there is that whether or not you intend to, you’re likely going to talk more than you should. This can mean risking losing the sale. For example, if the buyer asks about the hot water, you might accidentally let it slip that it doesn’t stay hot for too long. Too many little “slips” like this can result in the buyer walking away. Read: Open Houses That Work.
Also, make sure that your pets aren’t present either. No buyer wants to deal with your dog jumping all over them while they are walking around. Plus, some people are allergic to dogs, while others are scared of them, regardless of how nice the dog is. Better to be safe, rather than sorry. You don’t want to lose the sale because you didn’t feel like taking Fido for a walk, or dropping him off at the boarders for the afternoon.
Every once in a while, it may be okay for a buyer to be present. This is only in certain, and extreme circumstances. Your realtor will let you know if they feel it is necessary for you to be present. For further reading, see:25 Real Estate Open House Ideas & Tips from the Pros.