It is good at picking up heat behind the walls, good for a safety survey of your house.
The cold water dousing does change the surface temperature for a very short while.
So far, I do not believe it can see a body through a wall from outside, but it can detect temperature differences through 1 sheet of dry wall for sure.
I think all of the small critters are inside where it is warm right now. I didn't see any moving around.
We don't have much in the way of rocks around here, but I will try that if I go where there are some (sand hills around here).
It can't see through glass, it only picks up the reflections.