Yeah, but it ain't nothing that microwaves, space heaters, and hair dryers haven't already given a run for their money.

Hair dryers and microwaves only run for a few minutes, so even if you do have too much resistance this probably won't immediately reveal a problem. A space heater might, but most space heaters I've come across actually seem to draw not much over 1,000 watts.

And even then, even if you do run something 24/7 at max wattage, it's definitely not guaranteed to start a fire even if the wiring is bad. Like, as long as it's not egregiously bad, I'd expect that there's enough margin to cover up less severe issues in most cases. I'm guessing the most danger would come when it's particularly hot outside (especially since then you'll probably have a lot of heat exchangers running.)

As an old house owner, I can attest to that for sure. In fairness though, I suspect most of the atrocities occur in wall and work boxes, as long as your house is new enough to at least have NM sheathed wiring instead of ancient weird stuff like knob and tube. That's still bad but it's a solvable problem.

I've definitely seen my share of scary things. I have a lighting circuit that is incomprehensibly wired and seems to kill LED bulbs randomly during a power outage; I have zero clue what is going on with that one. Also, often times opening up wall boxes I will see backstabs that were not properly inserted or wire nuts that are just covering hand-twisted wires and not actually threaded at all (and not even the right size in some cases...) Needless to say, I should really get an electrician in here, but at least with a thermal camera you can look for signs of serious problems.