Finally got around to doing the plugs and leaking valve cover gaskets on my Infiniti. Here are a couple of the old plugs. I presume they are the original ones. What does the white crust mean?

 

Net says running too Hot (lean) timing or fuel mixture too lean.

 

Perhaps it's the photo's perspective but the gap on those things looks pretty big.

 

What about soaking the tips in carb cleaner and scrubbing with a nylon toothbrush?

 

+1 for lean and huge gap.

 

get new plugs and you are definitely burning too lean/too hot. How old are those plugs you had in the car, such as mileage you could been way over due on plugs change

 

You could do that to make the plugs look pretty, but it would nothing for the functionality. If you are going to do something to make the plugs work better, you need to dress the anode and electrode with a file and then re-gap.

 

I'd be willing to bet that gap is around .055 to .06
Probably original plugs.
Swap them with some NGK iridium plugs and be done with it. Assuming you're not having driveability issues at the moment.

You can always pull the front ones in a few miles and inspect them then. If it's a tuning issue the crust will return. It can be dealt with then.