Some stocks may make you want to wash your hands after hitting the "buy" button, even if you're making money. The opposite of these "sin stocks," on the other hand, leave you feeling good about your investment's impact on the world at large. Socially responsible investing can fill your pocketbook and let you sleep at night.

Digital music service Pandora Media (NYSE:P) has passed a strict screening process by financial analyst firm Calvert Investments and is now included in the prestigious Calvert Social Index list of corporate do-gooders. Many socially responsible investing funds are based directly on this index, making Pandora a popular holding for investors with a conscience.

Pandora stock is a socially responsible investment. No two ways about it; Calvert doesn't bestow this title unless the company passes all of the index's seven core criteria. That means caring for the environment, respecting human rights, producing safe products via safe processes, showing strong corporate governance policies, and much more.

So owning Pandora can boost your karma. But can Pandora shares boost your retirement portfolio, too?

Warning signs
Pandora's stock chart looks like a terrific roller coaster. I mean, build this beast, and I'd love to ride it. Share prices recently more than quintupled over a 16-month span only to get a nearly 50% haircut over the following eight months:

P Chart

P data by YCharts.

The net result of this thrill ride is still a market-crushing 137% return on the original investment, but this adrenaline rush isn't for everyone. Owning Pandora shares may save you money on sleeping aids, but it will also cost you a fortune in antacids.

The stock is jumpy for good reason. Investors generally love profits and hate risk. Pandora tends to lose money, and its future is anything but clear. Worse, the company burns cash on a regular basis and depends on secondary stock offerings to keep its balance sheet afloat.

Pandora also depends on a delicate balance. On one hand, the company must pay fair royalties to the artists and songwriters who fill Pandora's service with music. On the other hand, the company needs to make enough money to power its operations -- with a little something left over for investors. All of this needs to happen without giving Pandora listeners a sticker shock, sending them to rival services like Rdio, Spotify, or iHeartRadio.

So far, customers seem satisfied, and Pandora has paid out more than $1 billion in royalties. Investors have seen fewer reasons to smile.

Upsides
So far, so scary. Pandora's business seems brittle at first glance, leaving almost no room for profit-taking between the artist and the listener.

But stocks don't rise nearly 140% for no reason. Here's why investors see some light at the end of Pandora's profit-free tunnel:

P Revenue (TTM) Chart

P Revenue (TTM) data by YCharts.

Since going public in 2011, Pandora has grown its trailing sales by 300%. Meanwhile, profit margins may still be negative but have improved a lot in recent quarters:

P Chart

P data by YCharts.

Pandora boasts 76.5 million active listeners with a growing appetite for curated music stations. The listener count is growing 5% a year while active hours per user increased 18% year over year in the third quarter. Taken together, that's a 25% increase in listening hours.

And here's the best part. Advertisers are catching on to Pandora's growing reach, bidding up the cost per marketing spot by 12%. With all the puzzle pieces coming together, Pandora's total revenues rose by 40%.

All the trends are moving in the right direction. Pandora is already reporting positive earnings on an adjusted basis, and it might be able to turn its cash-burning ways around soon.

Is Pandora a good investment, then?
Pandora is not for the faint of heart, as the company still struggles against troublesome royalty rates and a boiling hot market for music services. Risks aplenty, Pandora shareholders still need nerves of steel.

But there's plenty of upside if you expect Pandora to overcome its structural challenges. The high peaks in the price chart speak volumes, and the average analyst's price target sits 60% above today's levels. Pandora may be the opposite of a safe investment, but it could still be a profitable one.

So, it's hardly a slam-dunk cash cow. But for the right investor, and with a steady hand on the firm's long-term rudder, Pandora could pay off handsomely. All it takes is a few lucky breaks -- and the backbone to hang on through the the wild ride that's coming ahead.

Anders Bylund has no position in any stocks mentioned. The Motley Fool recommends Apple and Pandora Media. The Motley Fool owns shares of Apple and Pandora Media. Try any of our Foolish newsletter services free for 30 days.

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