Veteran Motley Fool Hidden Gems members know what we love to find in a small company. Honest, competent management. Solid financials. High levels of insider ownership. Strong returns on equity and assets. Little or no Wall Street coverage. And a price that's right for long-term buyers.

What we don't often talk about, though, are the things that can go bump in the night. The traits of bad small businesses that make us fear and loathe them.

There are more than 3,500 public companies capitalized under $500 million. And sure, there are loads of great winners in that bunch, poised to rise many times in value. Look back, and you'll find companies such as Qualcomm (NASDAQ:QCOM) and PotashCorp (NYSE:POT), each of which gained well over 1,000% in the last 15 years.

These easy-to-understand businesses are the type that investing master Peter Lynch loved to own.

But let's not kid ourselves. Out of those 3,500 companies, there are tons of mediocre companies, and worse. Like Tolkien's terrible dragon, Smaug, they can incinerate your savings in no time. (Hey, we said this was scary stuff!) Quite seriously, if you're not doing business research and you don't know what to avoid out there, you could lose your fortune.

There were 570 companies valued at $20 billion or more in late 2007 before the credit crisis began to unfold. An incredible 136 of those -- nearly a quarter of them -- lost at least 50% of their value at some point. Besides financials like Bank of America (NYSE:BAC) or Fannie Mae (NYSE:FNM), that list includes the likes of Cisco (NASDAQ:CSCO) and Apple (NASDAQ:AAPL). When even these large guys can drop precipitously from their highs, you have to keep your eyes wide open.

Let's start with an example of what to avoid.

Case study: Charter Communications
In our active online community, a Hidden Gems member asked us a few years ago what we thought of Charter Communications, a broadband cable company whose chairman and largest shareholder is Microsoft co-founder Paul Allen. The business is also substantially owned by Wally Weitz, a Nebraska-based investor admired by Warren Buffett fans and who found great returns in stocks such as UnitedHealth Group and WellPoint (NYSE:WLP).

Charter Communications stock had fallen from $25 to $4.50, and our member wanted to know whether it was a good time to get in for a turnaround.

We'll start by saying that in Hidden Gems, we absolutely love the broken small cap that's poised for a turnaround. Show us a company whose stock has fallen 90% from its highs, whose chairman is a billionaire, and whose largest institutional owner is a close friend of Warren Buffett, and we'll sign up to do very careful research. That's exactly what we did with Charter Communications at $4.50.

But we did not like what we found. Here's why we warned against investing in this business:

  • Massive debt. Net debt (debt minus cash) was more than $18 billion.
  • Net debt was 28 times the company's market cap of $640 million.
  • Charter Communications was unprofitable, with $1.5 billion in yearly interest costs.
  • Debt covenants posed a serious threat to the company's survival.
  • The SEC had launched an investigation into its accounting practices.
  • Heavy spending for cable infrastructure hadn't yielded high enough returns.

Near the end of June 2003, Tom Gardner wrote negatively about this stock when it was trading at more than $4. It's tough to go contrary to Paul Allen and Wally Weitz. But there was no turnaround in sight, and the company's balance sheet was deteriorating. We've continued to warn investors about the company nearly every month for four years now.

The stock itself eventually cratered, and Charter Communications filed for Chapter 11 bankruptcy.

What we do and don't fear
Oddly enough, our Hidden Gems team does not fear high debt in and of itself. Our recommendation Middleby carried more than $100 million in debt after buying a competitor and repurchasing founder shares. Yet the stock has risen more than 400% since the original recommendation. The company's operations are plenty strong to repay those obligations.

Nor do we fear companies that have fallen far from their all-time highs. Indeed, each of these scary factors individually could make for a compelling investment as the stock price drops into the real value range.

So what was the problem with Charter Communications? We didn't like the scale of its debt, running north of $18 billion, alongside harsh payment terms and emerging accounting problems.

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This article was originally published on Jan. 13, 2005. It has been updated.

Rex Moore anchors the gold-medal-winning Motley Fool 4x100 three-legged sack race relay team. He owns shares of Microsoft and Qualcomm. WellPoint, UnitedHealth Group, and Microsoft are Motley Fool Inside Value recommendations. UnitedHealth Group and Apple are Stock Advisor picks. The Fool owns shares of UnitedHealth Group and Middleby. The Motley Fool has a disclosure policy.