How you behave at an open house just might make or break the sale for you. NY1's Jill Urban filed the following report.

At an open house sellers open their doors and hope buyers will feel right at home. But all too often, some buyers feel too at home and demonstrate poor open house etiquette.

"You’d be surprised at what I have seen at open houses. Buyers find it okay to bring their dog. I have seen buyers bring coffee and spill them on chairs. I have seen them bring their children and let them run wild in the apartment breaking things and dropping food as they go," says Corcoran Executive Vice President Karin Posvar Picket.

Posvar Picket is one of many brokers who says some buyers have no idea how inappropriate their behavior can be. For one, it is never okay to bring your dog.

"This is someone else’s home and you should not bring your dog. I have seen dogs get into fights, I have seen dogs have accidents. Sometimes sellers are allergic. It is just inappropriate to bring your dog," says Posvar Picket.

Strollers can be another issue. They can track in dirt and clog up hallways making it hard for other visitors to pass. As a buyer, you should ask if it’s okay first to wheel it inside. If not, keep a close eye on your child and don't let them run around with snacks in hand.

Also, leave all your food and drinks at the door.

Another pet peeve for sellers is when buyers help themselves to the bathroom. If you have to use the bathroom, you should always ask the broker if it is okay first and if it is, go quickly because people may be waiting to see that room.

Posvar Picket says as a seller if you are uncomfortable with something, it is absolutely okay to set some rules.

"To help your agent enforce your rules, if you don’t want coffee in your apartment, leave a tray out by the front door that they can put coffee on. If you don’t want shoes, leave a basket to put them in or medial booties to put on," suggests Posvar Picket.

At the same time, sellers can’t get upset when buyers start looking through closets, medicine cabinets and even the refrigerator. These are elements of the home they are looking to buy and are considered fair game to inspect.

Poor etiquette at an open house can make a seller angry and hinder a negotiation down the line. So when you visit an open house, you’re making a first impression too, so be sure not to check your manners at the door.