In case you missed it, the Wall Street Journal has an interesting profile out today on Mario Gabelli, the $89 million-a-year founder of Gamco Investors Inc.

The story details 73-year-old Gabelli's success over the years as a stock-picker and his steadfast commitment to a research-heavy process even as a growing portion of the investing public is throwing in the towel on stock-picking in favor of index investing. Yet there was one juicy tidbit that came and went without much elaboration and, well, let's see if you can find what it is:

"Mr. Gabelli, who is thin with white hair, spends much of his free time immersing himself in myriad subjects from quarry mines to adult diapers, which he considers a growing market because of the aging population."

Wall Street's highest-paid CEO is bullish on adult diapers! This is an investment theme that could spawn so many think pieces, like ... well, let's not go there (the jokes would be too cheap and easy.) Instead let's take a look at why diapers, both the adult and baby varieties, may smell like roses to investors like Gabelli. (OK, sorry for that one cheap joke.)

For one thing, it's not just the huge demographic of Baby Boomers who are following Gabelli into the white-haired years. It's also in emerging markets, where the runway for growth is much larger than the U.S., where the disposable baby-diaper market is saturated. (Sorry again. These cheap jokes can be hard to resist!)    

Sales of diapers in China and Eastern Europe rose 30 percent in the most recent quarter at Kimberly-Clark Corp., maker of Huggies for babies and Depends for their grandparents.  And get this -- while many multinational corporations like Kimberly-Clark are struggling with the strong dollar's effect on sales, this growth was driven by price increases meant to combat weakening overseas currencies. While diapers may indeed contain elastic, demand for diapers seems to be reasonably inelastic.

Gabelli's diaper play, however, is a more concentrated and bold bet. And frankly, it's been a real stinker of late. (OK, hopefully that's the last diaper joke.) Gamco has amassed a 16 percent stake in the small-cap Tredegar Corp., which makes the plastic films used in diapers.   

At first it worked out great: Gabelli took an initial stakeof about 6.9 percent in 1994, and the stock jumped more than 800 percent by April 1999. The shares crashed hard, however, and never quite reclaimed that peak.

The stock is down more than 50 percent from its most recent high in 2013 as the company's plastic-film business struggled with problems at a plant in Brazil and delays in the startup of a new product line.

As for Gabelli, this roughly $77 million position may not seem like much compared with the $47 billion Gamco manages or, heck, even the $89 million that Mario reportedly made last year. Yet it's clear this position is one that's close to Gabelli's heart. While Tredegar's conference calls are usually a short affair since not many analysts cover the stock, Mario himself has been known to make an appearance.  

"Hi, Mario. How are you doing?" former CEO Nancy Taylor asked on the earnings callin March.

"Not too bad," Gabelli replied. "I missed part of the call, because there are too many conference calls, but always wanted to listen to yours," he said before asking how the company was marking certain assets to market.  

This morning, Tredegar announcedthat its interim CEO will take over the top job permanently and the president of its film products business will leave the company.  The stock promptly fell and is trading at a three-year low.

Being a diaper bull can be a messy affair. (Sorry.)