Someone cooked an article of food in his kitchen in 2000. In 2010, he discovered that it was treif Gamur. Between 2000 and 2010 he changed all his cutlary, plates, etc. so that nothing that he owns is from the original "treifed" up cutlary.
However, Ashkenazim say that there is a halacha called Chaticha Naaseh Neveila Bshaar Issurim - which means that if kosher food absorbed from treif food, the kosher food becomes inherently not-kosher (not that it is a kosher article becomes forbidden to eat because it has not-kosher taste, but that it becomes trief, and when a piece of that kosher food falls into another pot of kosher, it needs sixty times the newly-unkoshered food).
Moreover, many are of the opinion that taste within the walls also become Chanan (Chaticha Naaseh Neveila).
So now, if the person cooked the not-kosher dish in a pot, that pot became treif. He turned around and washed that pot in a Yad-Soledes-Bo kiluach which was not nifsach, so other plates became treif too. That should now spread from plate to plate forever.
Moreover, Nosein Taaam Lifgam (or the twelve months heter) doesn't apply here, as each time the hot water landed on the pot, it becomes treif inherently and the 24 hour count starts again.
Is there a limit to how far Chanan goes?
PS. Not everyone agrees with the Shulchan Aruch, who holds that soap is Nosein Taam Lifgam.