Response to the above in red:
Interesting around here when we find space heaters (including those overly priced electric fireplaces), the most common problem is stabbed in the back receptacles, second is loose or corroded receptacle terminals, where the device is used for a splice point, which I don't do anymore as we pig-tail all receptacles now.
I would say for third place is a toss up between bad breaker stab connections, and loose splices in box's, and with box's where the wire is not twisted most likely results a burnt wire nut.