[masraum]

counterfeit spark plugs seems crazy, but yeah, they are a thing.

Best you can do is to only buy from valid sources, don't buy from eBay to get a deal, and if you buy from Amazon, don't buy from other sellers.

Although I think I've recently read somewhere, that if 5 different sellers including Amazon sell the same product, that the products are all pooled in one place on the shelf. So you could have 4 sellers selling legit stuff, but if one seller is selling counterfeit, then it's the luck of the draw.

I can see how ^that^ might be a thing that Amazon would do for efficiency, I also find it a little hard to believe that they'd pool their stuff with the stuff from essentially unknown sources.