Accent plugs are just standard copper plugs. The maintenance interval is
30k. Usually, they'll last 50% longer than that before misfiring, but
every once in a while, I see an issue even within the maintenance interval
Usually, when an aftermarket plug is misfiring, I find it's one of the
"junk" plugs you describe. That's one of the problems with places that
lowball prices. Often times they're able to do that because the use
low-priced junk. Despite the fact that I wouldn't ever recommend
aftermarket plug wires (and many disagree with me on that), there's
exactly nothing special about Hyundai plugs. In fact, you can probably
purchase better for a lower price somewhere other than the dealer.
Mostly, it's important to know that the place doing the maintenance and
repair on your vehicle is using quality parts so problems like this won't
continue to happen.