Hi, Bill,
I hope you don't mind my stepping in on this one. The blow dryer wattage issue got mixed in with the back wiring only as a matter of "what does a UL listing really mean?".
Anyway, back wires do seem to burn clear. To me that they burn at all when not really overloaded is indicative of a poor contact. And it just may be that a poor contact was made during the installation.
I didn't think that '66 was suggesting that backstabbing leads to receptacles like the one in the fixture.
Backstabbing could lead to refrigerator failure and intermittent connections in receptacles - but that might only be if not properly installed in the first place. The low contact area is suspect in my mind.
Regardless, there are better ways. Lug and set screw like a circuit breaker, and clamp and screw like a GFCI receptacle are two superior methods.
A was mentioned, the plastic faces break off those receptacles often enough, particularly at the "U" ground, that one might suspect that UL doesn't really abuse these things before certifying them.
