Not even the supremely hyped Facebook IPO could save the market from falling last week. That doesn't, however, mean it made a sizable dent in the number of stocks near their 52-week highs. For optimists, these rallies may seem like a dream come true. For skeptics like me, they're opportunities to see whether companies have earned their current valuations.

Keep in mind that some companies deserve their current valuations. Shoe retailer DSW (NYSE: DSW) logged a new high earlier this week after it reported blowout first-quarter results and once again boosted its full-year forecast. This is the kind of stock that can, in my best Arnold accent, "Pump ... you up!"

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

Take two of these and run away in the morning
There are few sectors that offer near-guaranteed cash flow like the insurance sector, and even fewer that have the long-term promise of the health care field. Mixing the two should seem like an instant winner, but that's not the case with online health insurance provider eHealth (Nasdaq: EHTH).

I can't say I completely dislike the company's business model, as anything that emphasizes consumer convenience in the health care sector has a good chance of being successful. What I am having a problem with is wrapping my head around eHealth's premium valuation. I'm not certain what investors are seeing in a company that reported a 1% decline in revenue and a $1.7 million decline in cash flow over the year-ago period in its latest quarter. For what should be a high-growth business, eHealth's earnings estimates on Yahoo! Finance signal that that's far from the truth, with sales growth expectations of just 2% in 2012. That's too steep a price to pay for 40 times forward earnings, if you ask me.

This is far from a sale
I've been hypercritical of retailers lately, and for good reason: Many artificially benefited from a warmer-than-normal winter, and their same-store sales figures aren't doing justice to the real health of the underlying sector. This is exactly what we witnessed recently with Gap (NYSE: GPS) when it reversed an 8% same-store sales gain in March to a 2% same-store sales decline in April. Now, it could be Dillard's (NYSE: DDS) turn to follow the same path.

Dillard's has escaped bankruptcy during the recession, and through heavy cost-cutting and a fresh mix of product has been able to go toe-to-toe with mall-based anchor Macy's, while stealing market share from the struggling J.C. Penney and Sears Holdings. Looking forward, though, sales growth is expected to slow dramatically (according to analyst estimates) to less than 1% next year. That's the good and bad about cost-cutting: It boosts near-term profits, but there's always a peak if there's no real growth. With its negligible 0.3% dividend yield, I'm perfectly happy passing on Dillard's at levels that have it priced for perfection.

Without foundation
The words "value" and "housing" may seem to go hand in hand for investors, but to me they're an oxymoron. It would be difficult to argue that any homebuilder has fared better than NVR (NYSE: NVR) over the past five years, but as we've learned, past performance is no guarantee of future results.

NVR's first-quarter results highlighted more of the same growth we've come to expect from the best of breed in the homebuilding sector: a 31% rise in new orders and a ridiculously low 10.3% cancellation rate. While it's very difficult to find any negatives in NVR's stellar results, I find it interesting that the company has missed Wall Street's EPS estimates for two consecutive quarters. Also, continued weakness in the Case-Shiller home price index signifies to me that investors are far too optimistic on a housing rebound. NVR is a solidly profitable company, but expecting its cancellation rate to lower any more or its orders to pick up further seems foolish (small "f"), and I'd consider selling here.

Foolish roundup
Valuation is always a reason to sell a stock, but this week it was the primary reason for all three companies. Usually, I'll feature money-losing ventures or materially weak businesses; this week, it's all about unrealistic valuations. 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?

Share your thoughts in the comments section below, and consider using the following links to add these three stocks to your free and personalized watchlist so you can keep track of the latest news on each company. And to avoid investing in stocks like these, consider getting a copy of our special report "The Motley Fool's Top Stock for 2012." In it, our chief investment officer details a play he dubbed the "Costco of Latin America." Best of all, this report is free for a limited time, so don't miss out!