I like electric space heaters, but: I bought a cheap Chinese one a few years ago that somehow rewired itself. Like, the “off” setting became “low heat”, “high heat” became “fan” etc. I took it apart to see how the fuck that could possibly happen. The dial switch included a little roller contact that moved over a printed circuit board sort of thing to determine the setting; if the heater got too hot (imagine that!) the switch solder would melt and then re-flow into a different pattern, causing the switch to work completely differently. Just unimaginably hazardous.