Momentum investors love to back companies with the wind in their sails. Contrarian investors typically pick up the cigar butts the market has tossed aside. So what do you call investors who turn against winners? Sourpusses? Shorts?

Over on Motley Fool CAPS, we sometimes call them the savviest investors around. When one of our All-Star members -- those whose stock-picking prowess places them in at least the 80th percentile of our community -- sours on a top-rated stock, perhaps we should take notice. Perhaps the member's found a chink in that highflier's armor, or a question mark in its financial footnotes. Or maybe it's just a hunch. That's why these tables aren't lists of stocks to buy or sell -- just starting points for further research.

Here's a list of stocks that some All-Stars have recently spurned:

Company

CAPS Rating (5 Max)

Est. LT EPS Growth

CAPS All-Star

Member Rating

Internet Initiative Japan (NASDAQ:IIJI)

*****

NA

synergize

90.53

Owens Corning (NYSE:OC)

****

15%

UltraContrarian

97.67

Arch Coal (NYSE:ACI)

****

39%

Kvedarna

99.14

Sinoenergy (NASDAQ:SNEN)

*****

NA

mavericktrading

99.97

Primus Guaranty (NYSE:PRS)

****

30%

d1david

99.96

Source: Yahoo! Finance; Motley Fool CAPS.

On average, 96% of all members rating these companies think they will outperform the market. So what might have turned some of CAPS' top players against these otherwise widely admired stocks?

Fear and loathing
Coal producers such as Arch Coal and Massey Energy (NYSE:MEE) have benefitted from higher coal prices and greater shipment volumes, which has even led to an upgrade in their credit ratings. Yet like many other commodities these days, they have been unable to hold back the tides of concern expressed by investors such as CAPS All-Star member 50day, who suggests that commodities' position is precarious:

The coal bubble is popping. Coal mining stock with a PE high [as] the Google! I should have made this call months earlier.

One of the concerns some critics have with T. Boone Pickens' plan to make natural gas the automotive fuel of the immediate future is the lack of filling stations that could service natural gas vehicles. These naysayers might want to take a look at China, where the use of compressed natural gas is far more prevalent, and CNG filling stations are commonplace. 

Sinoenergy has witnessed the opportunity that represents, and it's changing its business model to design, build, and operate CNG stations. It already operates eight such stations in central China's largest city of Wuhan, and it recently unveiled plans to have as many as 28 operating by the end of the year. That kind of growth makes CAPS member Dayve63 consider its current price significantly undervalued:

[Sinoenergy] just listed on NASDAQ and is a leader in China's drive for clean burning fuel in the form of CNG for vehicles. Additionally, the company sells storage vessels, converts gasoline vehicles to CNG hybrids and designs and operates retail CNG stations. Their PE is very low in comparison to its industry. They are projecting growth around 70%. They have doubled the number of retail stores in a year.

As Lehman Brothers imploded and Merrill Lynch ran to the embracing arms of Bank of America (NYSE:BAC), the market was left with a disdain for complex and risky derivative investments like those sold by Primus Guaranty. Earlier this year, credit default swaps were widely considered the next shoe to drop. While Primus's services may have been lucrative, CAPS member luebypopoff felt that this Motley Fool Global Gains recommendation was a difficult stock to support, in light of so many companies' shaky financial underpinnings:

I really like this stock. I think it is mostly misunderstood and has a bright future, but financials are headed down the toilet and [Primus] will get sold off in they hype as well.

Make lemonade from lemons
It pays to start your research on these stocks on Motley Fool CAPS. Read a company's financial reports, scrutinize key data and charts, and examine the comments your fellow investors have made all from a stock's CAPS page. We've seen the direction some investors have indicated they believe these companies are heading, but Motley Fool CAPS is more than what the pros think, even if they're All-Stars. Let's hear what you have to say!

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Fool contributor Rich Duprey has no financial position in any of the stocks mentioned in this article. You can see his holdings here. Primus Guaranty is a Global Gains pick. Bank of America is an Income Investor recommendation. Google is a Rule Breakers pick. The Motley Fool has a disclosure policy.