­Say you're smart enough to use a buyer's-agent from the start. He suggests a property that sounds like your dream house--but you look at the square footage, and you think it's too small.

He's been working with you for awhile, and he knows you well. He knows what quality of life issues you most value. He also knows the house, the area, the local amenities, the community, the history of the property. In short, he knows what you want.

This matches up down the line--except for that square footage. But the property also has a guest house, which, he suggests (knowing your needs), might more than make up for the small main house. He insists you're making a big mistake passing this up. Finally, to shut him up, you agree to go see it.

And guess what? It's perfect. He's worked with you enough to know what you want better than you know yourself.

And guess what else? He negotiates a fantastic deal for you.

Why? He was working for you--not the seller.