One great use of a high quality Thermal Camera is inspecting under bathrooms. When I inspect a home with a second floor bathroom, I like to look at the ceiling on the first floor under the bathroom area with my thermal camera.
This is also where being a Certified Level 1 Thermographer by the Infrared Training Center is important, so I can have an understanding of what I am seeing and what it might actually mean.
In this image, we see a cold zone, but that into itself is not unusual given I had also just tested the AC you see the AC register on the wall. But what did concern me were the small darker dots, indicating even colder points. Using a moisture meter, I found elevated levels of moisture where these dots were. Along with additional evidence I gathered during the home inspection, I could determine moisture was indeed entering the building structure from the upstairs bathroom.
If you hire a home inspector that is not using a high quality Thermal Imaging camera and a moisture meter, then your are getting an incomplete inspection. Anyone else is just looking around.