Rephrasing my question as requested:
I've managed to blow up 3 or 4 RPis, models ranging from the B (just 2 USB ports) to the B+ to the quad core. It always seems to happen when I plug or unplug the HDMI without removing the Pi 5v power first. The symptoms are always the same, increased current consumption, hotter main processor, no more HMDI output. I can still SSH in but they're running very hot - something is definitely wrong with them.
Has anybody seen any similar behavior, or do you know why this might be happening? Is there anything I can do to further diagnose what's happened to these units?