Clearwire (Nasdaq: CLWR) is on a roll this week. Shares have jumped 20% from Tuesday's closing prices, egged on by positive earnings report from the company itself, as well as from central partner Sprint Nextel (NYSE: S).

On the other hand, this drastic climb simply brought Clearwire back to price levels last seen, oh, ten days ago. The trampoline-like action begs the question: Are the resurgent bulls right about Clearwire's prospects, or should you listen more to the bears?

In the second quarter, non-GAAP sales rose 8% year over year to $294 million. Adjusted net losses were slashed in half, to $0.29 per share. The sales figure came in a bit light against Wall Street's estimates, but bottom-line losses were slimmer than feared. Moreover, management raised its full-year guidance for both sales and earnings. Hence, the market-price pop.

CEO Erik Prusch reminded investors that Clearwire is moving from the failed WiMax 4G networking gamble and over to the competing LTE standard. The change, Prusch said, is key to "unlocking the value of our deep capacity resources and uniquely position us to meet the short and long term needs of consumers and wholesale carrier partners." The company even enlisted independent market research firm IDC to provide supporting statements for this theory. You just don't see that very often in an official earnings release.

But the positive story falls apart when you dig below the relatively shiny surface. Clearwire burned $272 million of free cash, or about twice the size of its negative GAAP earnings. The company lost more subscribers than it signed up during the quarter. It's hard to overlook the $4.2 billion of long-term debt weighing on Clearwire's modest $1.2 billion in cash equivalents. And I have to question the company's commitment to building a state-of-the-art LTE network, while capital expenses are falling year over year and are not large to begin with.

This company is not a totally hopeless case, yet. Clearwire, for example, is working with chip designers Qualcomm (Nasdaq: QCOM) and Sequans to ensure that its LTE standards are compatible with similar technologies used in China. Clearwire could become the default roaming option for Chinese travelers going to America -- but only if other networks don't decide to support Chinese roaming the same way. And, if the company's IDC-supported claims about unmatched bandwidth efficiency turns out to have legs, I could see marketing in the vein of those classic "Can you hear me now?" spots for Verizon making a difference.

But the potential catalysts come with loads of unanswered questions and risky all-in bets. That's why I stand firm on my thumbs-down CAPScall on Clearwire, which has already boosted my overall CAPS score by 49 points in less than 10 months. The real winners in the trillion-dollar mobile revolution can be found elsewhere. Click here to read a special report on how to play this once-in-a-lifetime opportunity.