You're not "that guy" at all. It's quite the opposite. Most people (myself included) have no clue what a dry hit is as well. In fact, people who vape often have the reputation of being "that guy".

I don't know enough about how these things work to verify his comment that metal is only a concern if you dry hit, but a dry hit just means it ran out of juice and you didn't notice, so you accidentally inhale a disgusting taste of burnt metal/fabric, rather than vaporized liquid. Normally though, you have liquid sitting in a tank touching metal, glass and/or plastic. Maybe glass and good metals don't leach into the liquid, but there are tons of cheaply made devices out there, and I wouldn't bet my health without seeing better studies that some sort of metallic or plastic compounds couldn't leach into the liquid, to then be vaporized and inhaled.

My understanding is that the metal doesn't get hot enough to bind to end up in the vapor in any quantity as long as the heating element is immersed in liquid. A "dry hit" is when you take a drag on the device when there is no liquid or not enough liquid in contact with the heating element. It tastes terrible, burns out coils faster, and burns your throat.

The only study I've seen that shows that heavy metals in vapor is an issue used conditions that are unlikely to occur in "real life" because of this. The argument seems to be that one could become accustomed to it through the cravings associated with nicotine withdrawal, but I honestly find that unlikely. In reality, you'd burn your coil up in short order, and if you can afford a new coil you'd have been buying more liquid in the first place.