If you hear an agent or broker complaining that a significant number of his "deals" fall through before closing, it could be that too many "closing techniques" are being used and they're experiencing "buyers' remorse." There are a good number of ways a buyer can balk on a contract without just saying "You pushed me too hard, and I've changed my mind."
Agent forums see this question frequently; "Do you lead your buyers through the home pointing out features, or do you just let them find their way and stay behind them?" If your buyers express that they'd like you to lead them around, then do it. Otherwise, they'll probably appreciate your presence to answer questions without too much feature-pointing. If you've developed a good relationship, your comments are probably appropriate, however, you don't have to like or dislike the home....they do.
Definitely point out problems you might see. Cracks in walls or floors, as well as mold or water marks are things you should bring to their attention. They still may like the home, but they'll need to get disclosure and inspection on these items if moving to purchase.
