The broad-based S&P 500 may be nearly 4% off its all-time highs that were set last month, as worries mount about when the Federal Reserve will begin paring back its monthly bond-buying program; yet, nearly 2,300 stocks are within 10% of a new 52-week high according to the Motley Fool CAPS Screener. For skeptics like me, that's an opportunity to see whether companies have earned their current valuations.

Keep in mind that some companies deserve their current valuations. Retailer VF (VFC 0.16%), for instance, hit a new 52-week high after outlining its plans during its investor day conference to increase EPS by 67%, and sales by 50%, between now and 2017. VF plans to hit these lofty targets by focusing on its Asian operations and relying on outdoor-action segment growth. 

Still, other companies might deserve a kick in the pants. Here's a look at three companies that could be worth selling.

Don't get too excited
I've witnessed far too many promising early-stage drugs turn out to be failures; so it's hard to get too excited about Cytokinetics' (CYTK 0.83%) expanded partnership with Amgen (AMGN 0.22%).

Announced yesterday, Amgen will be investing $15 million upfront in Cytokinetics, and will purchase $10 million worth of Cytokinetics' stock, becoming its seventh-largest shareholder. It also sets Cytokinetics up to receive as much as $50 million in additional royalties if the drug is eventually approved. The motive behind Amgen's move is their ongoing collaboration in stable heart failure drug omecamtiv mecarbil, which demonstrated encouraging phase 2a results . However, I see other reasons to keep your expectations tempered.

To begin with, omecamtiv mecarbil has shown a statistical effect in patients, but overall survival benefits, safety, and tolerability are yet to be determined. If this were a nine-inning baseball game, we're heading into the top of the third! If omecamtiv mecabril has any setbacks, you can rest assured that Amgen will split, and Cytokinetics will be decimated with only two other compounds in its clinical pipeline.

Also, even with Amgen covering the costs of omecamtiv mecarbil's early stage trials, Cytokinetics is going to quickly burn through its $61.6 million in remaining cash. By my estimates, it has -- even with Amgen's $15 million upfront payment -- less than two years of cash remaining. This means a dilutive secondary offering could be right around the corner. I'll keep my fingers crossed for success, but I certainly wouldn't be a buyer of Cytokinetics at these levels.

What a snoozer
It wasn't that long ago that Vanda Pharmaceuticals (VNDA 3.12%) was on my Watchlist as a value company that was trading right around its cash on hand. How times have changed!

Vanda's shares have soared following positive late-stage results for tasimelteon, the company's non-24-hour disorder drug meant to help blind persons who have no light perception regulate their sleep patterns. In trials, tasimelteon helped reduce daytime napping by 46 minutes per day in the worst 25% of days in a cycle, and increased nighttime sleeping by 57 minutes per day in the same period. The drug is anticipated to help between 65,000 and 95,000 persons in the U.S. who have non-24-hour disorder, of which there currently is no cure.

While the data would certainly suggest that the Food and Drug Administration will look good and hard at approving tasimelteon, Vanda didn't exactly maximize the value of its schizophrenia drug Fanapt, which has dealt with flat sales in a very crowded market. Who's to assume that this time around tasimelteon will be any different? Although there aren't any competitors to treat the disease, will Vanda be able to turn a profit, and maximize shareholder value on such a small group of prospective patients? Vanda's trial for major depressive disorder with tasimelteon failed to meet its primary endpoint four months ago, and the fact that it will be going it alone on marketing costs for non-24-hour disorder is only more proof that Vanda will have a hard time turning a profit. Vanda would have to get the pricing and launch just right, which is often very difficult to gauge.

Needless to say, I'd suggest passing on Vanda after this recent run-up in the share price.

Red Robin ... RUNNNNNNN!
Regarding the burgers, I say "Yum," but regarding the stock, I say "Run!" Red Robin Gourmet Burgers (RRGB 1.59%) has certainly delivered for investors over the past three years, with 11 straight quarters of higher same-store sales. The payroll tax holiday previous to this year, and an improving economy, gave Red Robin the perfect conditions to emphasize its value, and bring customers into its restaurants. However, the stock looks grossly overcooked now, with the prospect of higher expenditures and rising costs on the horizon, coupled with higher taxes.

The big factor that worries me most is that most consumers don't have the same level of disposable income that they had last year. This should translate into fewer restaurant visits, meaning Red Robin will need to focus heavily on menu innovation and specials in order to drive traffic through the door.

Also of concern is the fact that the company expects to drive profit growth through cost-cutting. There's nothing wrong with improving supply chain efficiency and in-store operations, but, when coupled with its plans to spend extra on platform expansion next year and into 2015, it could become a serious drag on Red Robin's top and bottom line.

This is one of those cases where I agree that management needs to take the moves it's making to stay ahead of the curve, but also feel that the valuation doesn't make any sense given the slowdown in growth that shareholders should be expecting in the not-so-distant future.

Foolish roundup
This week's theme was all about looking past the frosting to see what's really in the cake. For Cytokinetics, it's a sea of still unanswered questions about survival benefits, while for Vanda, it's whether or not it can control its costs and capitalize on tasimelteon if approved by the FDA. Red Robin, as well, has questions to answer about near-term growth, with the prospect of higher spending on the horizon, and cost-cutting actions already in place.

I'm so confident in my three calls, that I plan to make a CAPScall of underperform on each one. The question is: Would you do the same?