For me it was the ridiculously priced silver-bearing conductive grease. I poo-pooed it on AA and a dealer challenged me to try it and report back. I ended up eating a big plate full of crow when the paste proved to be an amazing tweak that I use to this day on any electrical connection in my system. Of course, I found out it's also used on large industrial machines and was way overpriced by the manufacturer, but that doesn't take away the fact that the stuff works. Anyone else have an experience like that where you were skeptical, but pleasantly surprised by a tweak?