A fascinating piece in today’s Wall Street Journal about a Japanese collector of North Korean garbage got me thinking about the value not just of garbage in a normal investigation, but to take a minute and to ask, ‘What is garbage?”

First, the article: Stuffed into a rented room near Tokyo are all kinds of cigarette packages that indicate class divisions in a supposedly classless society; ration books from a country that has suffered numerous recent famines; even an old phone book that cost $2,000 on the black market. A Korean-speaking history professor in Japan has collected it all, mostly from trips to the part of China that borders on North Korea.

Our clients sometimes ask us how we gather information when public records, databases and interviews don’t get us everything we need. One option we sometimes discuss (but very rarely get hired to do because of the expense) is to go through the garbage of people related to the investigation.

Picking up someone’s garbage is a complicated endeavor, in addition to the unpleasant task of physically sorting through it. Not only do you have to figure out where it gets left and when, but you need to make sure that you have the right to collect it at all. If it’s on private property, you are trespassing and stealing if you take it. Even if abandoned on public property, some states may still frown on the idea of taking it.

Appreciating the value of garbage can help an investigation that goes nowhere near a trash can.

Garbage is something that was once considered important to its owner but no longer is. But just because the owner doesn’t care about it doesn’t mean the rest of us cannot find use for it. That’s easy to see if you spot some nice piece of Danish furniture put out on the curb, but it applies to information too.

Think about a summer cottage purchased years ago by a married couple. Along the way the marriage sours and the husband begins to skim money out of the family business into a secret company he founds. The couple sells the cottage as the children grow up and move away, and then divorce proceedings commence.

When the wife approaches us with the suspicion that her husband has hidden assets, we take a look at his entire profile of both today and years past. We search the names of companies linked to the address of the former cottage and find a company was once based there but now has an updated address.

That is probably the one hiding the company assets, and that is garbage picking: an address no longer of use to the husband, but linked forever to the company he once founded and which is still very important to him.