EVERY saleswoman will tell you that the customer is always transparent. Maybe not entirely, completely, but compared with the poker face a buyer thinks that he or she is wearing, there are always expressions and signals that are obvious to the practiced observer.

When I first started out in Manhattan real estate sales, my boss shrugged and shared one of his favorites with me. “People with clipboards,” he said, “never buy.”

Whenever I tell that anecdote, I get resistance from someone who claims to have been carrying a clipboard right before buying a kazillion-dollar-apartment in One57, and if I weren’t so quick to jump to conclusions, why then I’d have my own yacht. But in my experience, it is true that buyers and sellers of real estate send readable signals — the equivalent of poker “tells.”

While every sale is different, there are also discernible stages that a customer goes through on the way to a transaction. A check with real estate brokers around the country indicates that many experienced ones “read the minds” of their customers — and can use their knowledge of consumer behavior to steer a market participant toward (or away from) a sale.

“Here’s a tell,” said Jim Foote, who has been in real estate for 38 years and is broker-owner of Greenwich Custom Real Estate Services in Old Greenwich, Conn. “If they linger for a long time in any one room, that’s telling you that there is something about this room that’s especially interesting to them.”

Conversely, a speed-through is often a sign of lack of interest. Mr. Foote has a current listing of a four-bedroom ranch house in Old Greenwich, on the market for $1.625 million. “If the progress from the hall through the living room, where the first fireplace is, through the dining room to the kitchen, through the family room where the second fireplace is — if that circuit takes two to three minutes, that’s pretty good,” Mr. Foote said. “If it takes 30 or 45 seconds, that’s not so good.”