It seems like NGC may have stumbled upon something fantastic! A cure for those dreaded white spots and toning that often develop on the mirror finish of some Pandas. http://www.ncscoin.com/news/viewarticle.aspx?NewsletterNewsArticleID=1223 "Modern commemorative coins can frequently be found with hazing residues that can be both unattractive and distracting. Proof quality coins can be frequently seen with the effects of poor storage and handling but mint state strike coins can also develop the dreaded haze. Just as with proof strike coins, the mint state strike versions can be adversely affected by the presence of heavy residues." This is amazing! I think I'm going shopping again!
In this example, it is toning (oxidation) and haze that NCS removed. This capability is proven and very reliable. Never hesitate to buy a Panda with toning and/or haze if you plan to send it to NCS. They will remove it. However, the White Spot of Death (WSOD) is fundamentally different from toning and haze. So far, NCS has not been able to remove it, or prevent it to appear. What they seem to be able to do is prevent more spots.
