Yes, I know.....
3 months after buying a multistarred item, I'm having trouble starting. One plug gives a nice bright 'star' spark. The other one a miserable yellow fizzle. Swap plugs from side to side and the fizzle goes with the plug. Put the somewhat old and carbonised NGKs back in and equal healthy sparks and instant start.
So the poxy things are in the bin. One had a nice clean ceramic, the other was discoloured in a strange way. A browny orange haze around the tip. Not carbon and I can't imagine one plug suffering contamination and not the other.
The dual english/ russian langauges on the box should have warned me. The plugs looked perfect and comparing with online pics showed no difference to real NGK. Live and learn (again).