Infra-red non-contact thermometers have been used extensively on television shows such as Ghost Hunters and others.  Keep in mind that IR Thermometers take their reading from a physical object that the IR beam makes contact with.  So, if trying to use an IR Thermometer to detect or measure cold spots the beam actually passes through the cold spot (if present) and provides a reading of the surface temperature of the physical object it first makes contact with.  Since a cold spot is not physical, you cannot effectively read the temperature of it with an IR Thermometer. It is possible the "cold spot" you detect with this type of thermometer is simply an exterior wall or window on the other side of the room, and not what you may think...

Instead, an ambient air thermometer should be used to measure the air in a given area.  However, keep in mind that most ambient air thermometers or temperature probes slowly adjust to the temperature around them to provide an accurate reading.  We use a cheap thermometer/humidity sensor you can purchase at places such as Walmart for reading the baseline temperature and humidity in a room, as you can let it adjust for 5-10 minutes to the room you are currently investigating and get a pretty reliable reading.

If your goal is to try to measure cold spots or warm spots that may come and go rather rapidly, you may need a more specialized thermometer such as the PT100 pictured below.  This thermometer can take accurate temperature readings to +/- 1 degree F in one second or less.  If a cold spot is felt, you can easily, quickly, and accurately measure the temperature differences inside and outside of the area.