I'm not a trained electrician, but I got my hands on a thermal camera to play with. Its existing documentation didn't help me quite understand what's going on when I see a hotspot. What components can I ignore when they get hot? What components typically heat up on a PCB as soon as power goes on? I know that heat is caused by current, so I kind of expect anything current flows through is heating up. Should ground leads be hot (in the temperature sense) where they touch your chassis or whatever you're using as a ground?
Let me get more specific. A small amplifier (based on the TDA2003) I'm using has a very hot resistor (compared to the rest of the circuit) as soon as power is on, and eventually the main IC and pieces of the PCB nearby heat up too. Is this sort of a case-by-case basis where it depends on my circuit diagram, or are there general rules of thumb when looking at thermal imaging of circuits?
EDIT: Attaching some images as requested, first is visible circuit, second is immediately after power on, third is after 2 minutes on.
Circuit schematic from CanaKit:
(Original source of instructions above: Imgur)