Mr. Pink,
The assessment is correct. I worked in the IT dept. at FLIR Systems Inc in Portland, OR in 1990. I leaned about the device and its operation from the VP of mfg, who was a total engineer-type.
IR is impervious to "reflections". The only thing it sees is HEAT. However, the FLIR is so sensitive that it can show the trace outline of your shoe print on a tile floor, and you can see individual hairs on your head.