Ahem... in my opinion, there's always "another interested buyer", and I always say so. That gives the buyer the sense of urgency to follow up on the deal if they are really interested. The flakes never call back.
I benignly advertised my rental house slightly below market value and had lots of phone calls but no lookers. I jacked the price up another $250/month and started telling callers I already had an interested renter, but would still show the house just in case they didn't take it. The second caller after that looked and took the house on the spot!
