Sin stocks can be serious moneymakers. As a father and husband who would cringe if any of his family members started smoking, the Fool's Brian Stoffel says investing in cigarette companies doesn't sit right with him -- but he doesn't hold it against people who do.

And he's not the only one who thinks so. Castle Focus Fund (NASDAQMUTFUND:MOATX) has a mutual fund that simply invests in companies it believes have the largest moats -- or sustainable competitive advantages -- around them.  

The fund is still relatively young, and not surprisingly for a value-focused approach, has underperformed the market since opening up in 2010. But when you look at how portfolio manager Robert Mark has done over the long run with a similar approach, his portfolio has returned 250% since 1999, versus the S&P 500's return of just 48%.

Not surprisingly, sin stocks are at the top of the list of Mark's investments. One cigarette company in particular, Phillip Morris International (NYSE:PM), has a pretty large allocation in Mark's fund. In the following video, Brian explains why the company is such an attractive choice for investors.