At The Motley Fool, we poke plenty of fun at Wall Street analysts and their endless cycle of upgrades, downgrades, and "initiating coverage at neutral." While the pinstripe-and-wingtip crowd is entitled to its opinions, we've got some pretty sharp stock pickers down here on Main Street, too. (And we're not always impressed with how Wall Street does its job.)

Given this, perhaps we shouldn't be giving virtual ink to "news" of analyst upgrades and downgrades. And we wouldn't -- if that were all we were doing. Fortunately, in "This Just In," we don't simply tell you what the analysts said. We also show you whether they know what they're talking about.

Today, we're going to take a look at three high-profile ratings moves on Wall Street: upgrades for Frontline (NYSE: FRO) and iRobot (Nasdaq: IRBT), and a downgrade for Clearwire (Nasdaq: CLWR).

Frontline's new rating: hold
Shares of Frontline got torpedoed late last year when, in a last-ditch effort to avoid bankruptcy, the company announced it was splitting itself into two companies -- "Frontline" and "Frontline 2012" (now a Frontline subsidiary).

Dahlman Rose announced yesterday that "after the successful completion of its restructuring," the firm was now willing to remove its sell rating on Frontline stock and upgrade the shares to hold. Dahlman warns, however, that the tanker market is likely to be "weak for at least the next 12 months," and is not yet ready to buy the stock.

I agree. While Frontline's reshuffling of assets appears to have relieved the company of a substantial portion of its debt, the company remains unprofitable and free-cash-flow negative at last report. Before buying into a promised turnaround, I'd at least like to see a full quarterly statement of operations from the "new" company, to get a better picture of what we're working with. Examining the company post-restructuring, Fool alumnus Stephen Simpson recently opined that what remains of Frontline is a "gutted" company earning "substantially lower charter rates" on its vessels. Even if the tanker market does rebound after a year or so, there's no guarantee Frontline will benefit.

iRobot's new rating: buy
A more optimistic upgrade goes to iRobot this week, as broker Brigantine upgrades this stock to buy. Details on this upgrade are scarce so far, but here's what we do know: iRobot has beaten investor expectations time and again these past couple years. Still, the prospects for future outperformance look slim.

Overseas, military operations have concluded in Iraq, and U.S. troops are scheduled for a pullout from Afghanistan in two years. Both of these developments threaten iRobot's warbots franchise. Meanwhile, here at home, the Great Recession -- technically dead and buried in June of 2009 -- continues to shamble about the countryside with zombielike, undead persistence.

Brigantine may see this situation as favorable to iRobot. But with the stock trading for about 22 times earnings, and pegged for 22.5% long-term growth, the best I can say about iRobot is that it might be fairly priced today. What's more, I can't shake the feeling that iRobot's free cash flow, which currently backs up only half the company's reported net income, isn't as robust as it needs to be to justify the stock price. Honestly, the best rating I could give iRobot in this situation is a hold, and I'd be much more inclined to sell the stock.

Clearwire's new rating: hold
And speaking of the walking dead, we come now to the day's featured downgrade: Clearwire. StreetInsider.com reports that Kaufman Bros. is downgrading Clearwire to hold (and chopping 60% off its target price!). The reason: "Total revenue outlook for 2012" is dropping from $1.7 billion to $1.3 billion, and the earnings picture is even worse. Kaufman sees Clearwire losing $334 million in "adjusted EBITDA" this year, an 11-fold increase from previous expectations.

Now, the analyst does believe that a new agreement with Sprint (NYSE: S) will help Clearwire turn EBITDA-positive in 2014, which I guess is why Kaufman isn't counseling an outright sale of the stock. Still, if memory serves, EBITDA refers to earnings before interest, taxes, depreciation, and amortization charges are taken out. Such charges amounted to more than $1.3 billion at Clearwire over the past 12 months, which suggests that even an EBITDA-profitable Clearwire may not earn any net profit... even by 2014.

Unprofitable, burning cash, and laden with $3.3 billion in net debt, Clearwire should be downgraded. My only quibble: I wouldn't stop at hold. I'd ratchet this rating all the way down to sell.