What makes you sure it was the swap itself and not the old wiring behind it? I've seen plenty of outlets that were installed fine and still started arcing because the wires were loose or the box was packed with dust and junk. The $3 fix versus the $150 guy is the wrong question, the real one is whether whoever does it knows how to check what's already back there.

Honestly, I used to think the whole “real world testing” thing was overhyped, but hearing how your swap meet changed your process makes me want to try it myself. That hands-on approach sounds way more useful than my old lab setup.

Eh, it's two weeks, not a dig career. Lighten up.