Here's another danger of relying on a four-year old reference.... from personal experience.

In 1999, I published a catalog on Puerto Rico casino chips ... which has not been updated in five, going on six years (although I'm attempting to get a revised issue out by the end of this year).

I've seen references on ebay where the seller accurately states "not listed in Black's Puerto Rico Catalog" in an attempt to boost the bids received. Of course it's not listed in the catalog if the chip was released by a casino well AFTER the publication date.

Is this not a form of misleading potential bidders ... yet the statement by itself is accurate?