Not long ago, my real estate partner, Rachel Myrick, and I showed 7 houses in a day. It was chilly outside, wet, muddy, etc. You get the picture. Of the 7, almost half were vacant. One of the vacant houses had the thermostat set to around 58 degrees F. The house was listed for over $500k. It wasn't a short sale or REO. We didn't stay inside the house for long. We were uncomfortably cold. What a shame. It was really a nice house. I believe that if the thermostat was set to at least 68 degrees F we would have stayed longer and the house would of made more of a positive impression on our clients. I don't know why the thermostat was set so low and I didn't ask, but it appears that the home owner was saving pennies over the possible sale of the house.
Again, over the weekend, I went to a home inspection in a vacant house. The old round Honeywell thermostat was all the way to the right. That's about 45 degrees F. It was literally warmer outside than it was inside.
My advice to listing agents is to convince your client to let you keep the thermostat up at a comfortable temperature.