I have NGK plugs sent to me directly from NAPA of Mexico and occasionally they have that white powder on them.
I really doubt counterfeit NGK plugs are common in the USA, unless you buy them off of eBay or "some dude".
I've detected three sets of counterfeit plugs in five years installed in customer's cars:
First set was a NGK number that doesn't exist, the plating was plain shiny zinc, the lot numbers were crooked, and the lithography was fuzzy.
Second set was a NGK number that isn't sold in Mexico, and just like the first set the plating was plain shiny zinc, the lot numbers were crooked, and the lithography was fuzzy.
Third set were just plain terrible, they lasted 10 days. They were counterfeit ACDelcos, the plating was gold colored cadmium, the flash over ribs were missing just like a garbage Splitfire, the insulator on the terminal side was oversize, and the lithography was fuzzy, deformed, and a strange shade of blue.
The easiest way to tell genuine NGK: The plating should give off blue and pink hues, depending on how the light is hitting it. This is due to the triple plating process, very difficult to replicate.
