Hundreds of stocks are hitting new highs lately, and earlier this week I singled out five of them that I felt were just getting started.

Now I'm going to tap my inner pessimist to scour that list of 518 NYSE and 308 Nasdaq stocks for investments that I think are peaking.

Let's go over a few highfliers that I see headed lower.

 

Oct. 13

High

Low

Weight Watchers (NYSE: WTW) $32.25 $32.74 $24.39
comScore (Nasdaq: SCOR) $23.24 $23.84 $12.64
Travelzoo (Nasdaq: TZOO) $27.08 $28.26 $10.29
Crocs (Nasdaq: CROX) $14.34 $14.94 $4.33
NetScout (Nasdaq: NTCT) $21.43 $21.80 $11.75

Source: Yahoo! Finance.

Let's go over the reasons to be skeptical of these stocks.

Weight Watchers
I understand the buy thesis for Weight Watchers. We've let ourselves go in feel-good comfort food during the market downturn. Once we can afford to wean ourselves off fatty dollar-menu burgers, folks will be turning to dieting and other weight management solutions. Weight Watchers will be perfectly positioned, like shooting Filet-O-Fish in a barrel.

Weight Watchers is also an intriguing buyout candidate. If chocolate giant Nestle made the ironic purchase of Jenny Craig four years ago, why can't Weight Watchers smoke out a suitor?

Unfortunately, the thesis falls apart when we begin to consider the company's growth prospects. Analysts see earnings declining on flat revenue this year. They see modest growth in 2011, but Weight Watchers is still projected to earn less next year than it did last year.

In its latest quarter, paid weeks were up year over year, but attendance was sharply lower. Yes, we'll be looking to lose weight eventually, but this doesn't necessarily mean that it will be through Weight Watchers.

comScore
I do lean on comScore analytics to get a firmer understanding of Web traffic trends, but I also know how to read momentum.

Three months ago, analysts figured that comScore would earn $0.23 a share this year and $0.44 a share come 2011. Now the pros have marked those targets down to $0.06 and $0.28, respectively. How can a stock head higher, when the fundamentals are heading lower?

It gets worse. The company has actually missed Wall Street's expectations in two of the past four quarters.

It's not as if comScore is a darling in its niche. It blew its call on the world's largest search engine two years ago. It also took months to correct an exploit in its search traffic tracking earlier this year.

In short, the party hats are premature here.

Travelzoo
I've been a bull on the travel-deals publisher behind a weekly top 20 email of sponsored vacation bargains for years. However, it may have overrun the runway this time.

Shares of Travelzoo have more than doubled since this summer, giving it a rich valuation that it doesn't exactly deserve at this point in its growth cycle. Is Travelzoo worth 45 times this year's earnings and 34 times next year's mark? Its top-line growth warrants a more conservative approach, and one that should handicap the shares given the low barrier to entry.

Even travel portal priceline.com (Nasdaq: PCLN) -- the perpetual darling in this niche over the past few years -- trades at substantially lower profit multiples despite higher projected revenue growth.

Crocs
Those who figured that the maker of fashionably dubious resin footwear would be dead by now are wrong. Crocs is still alive, and actually thriving in certain world markets. Rip up those death-pool tickets and aim elsewhere.

Crocs has thankfully updated the look of its shoes, retaining the comfort that made them popular in the first place. It's working. The shoemaker has blasted past Wall Street's net income expectations in back-to-back quarters, and the market is buckled in for healthy near-term growth.

But I'm uncomfortable. I've seen Crocs take a blow when it seemed as if everything was humming along nicely, and I don't want to get burned again. This remains a fickle market, and I'd rather buy at the lows and sell at the highs.

Yes, Nike (NYSE: NKE) is also trading at fresh highs, but the "Just Do It" athletic footwear giant has managed to remain relevant for decades. Crocs has simply gone in and out of style, and then back in, all in a short span of time.

NetScout Systems
Some websites can't afford to go down. Between online brokers in an industry where timely order execution is huge and government defense platforms that can't let down their guard, NetScout specializes in monitoring a website's uptime.

Consolidation in cloud computing is sending a lot of shares higher, but NetScout doesn't really fit the mold of a Web-savvy speedster. It's been a slow grower this fiscal year, and analysts see revenue and earnings inching just 9% and 12% higher, respectively, come fiscal 2012.

I loved NetScout in the single digits last year, but I can't back it as a worthwhile investment at more than twice the price.

Weight Watchers International is a Motley Fool Inside Value recommendation. Nike and priceline.com are Motley Fool Stock Advisor selections. Try any of our Foolish newsletter services free for 30 days.

True to its name, The Motley Fool is made up of a motley assortment of writers and analysts, each with a unique perspective; sometimes we agree, sometimes we disagree, but we all believe in the power of learning from each other through our Foolish community.

Longtime Fool contributor Rick Munarriz realizes that you don't know you've hit your peak until you're going downhill. He does not own shares in any of the stocks in this story. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.