Spark Plugs ARE Important

So my stepson tells me his car has been getting a random misfire code and wanted to know if I could help him figure out the problem. It didn't take very long to solve it for him.

http://usera.ImageCave.com/ydfah/vehicles/6 Spark Plugs.jpg

Those are about the worst I have ever seen.
I wonder if the damage is caused by detonation? They seem awfully far gone for just regular wear, even if they are old.

Thanks for the lesson, alloro. Those plugs are really gone....I wonder how poor the fuel mileage was.... so many parts we take for granted as "still good". No substitute for regular tune-ups, eh?

its a wonder the spark jumped that gap! looks like some of the spark plugs from my extended family's vehicles (lol)