Thermal Imaging

Seems like a lot of info is around on thermal imaging now. Have many of you had a client ask for it, and inspectors are you dong enough of them to pay for the gun? What about the liablity of not finding a problem after you use it and or do you scan every squ ft of the building. If the temp. range is 11-13 degrees and the colours are from dark blue to red hot is it a issue?? Thanx, Chuck.