Some contend that shorting stocks is un-American. Hardly. Selling short provides liquidity to the markets, aids in price discovery, and provides an extra check -- some argue the only check -- against ill-conceived business ideas and incompetent executives.

New York Stock Trader Dave Fischer is a short king, and has made most of his money over the past 15 years shorting stocks. His favorite phrase is, "With those fundamentals, that stock can't hang on for long."

Late Tuesday, Carnival Corporation (NYSE: CCL) reported that it will temporarily cancel all stops in Mexico due to fears surrounding the swine flu. "We have decided to cancel calls at Mexican ports for all current sailings. Additionally, we will cancel calls in Mexico for all voyages departing Thursday, April 30 through Monday, May 4," the cruise line operator said in a statement.

Carnival isn't the only cruise line playing it safe. Sector peer Royal Caribbean Cruises Ltd. (NYSE: RCL) also announced plans to temporarily suspend port calls in Mexico. Currently, the World Health Organization (WHO) has not recommended any travel restrictions to halt the swine flu's spread.

Famous cruise line entity Carnival Corp. (NYSE: CCL), which competes with Royal Caribbean (NYSE: RCL) and The Walt Disney Company's (NYSE: DIS) vacation voyages, reported earnings for the third quarter on Thursday. The company held up well during the summer months. Revenues increased 11% to $4.8 billion. Earnings per diluted share did decrease slightly from a year ago, dropping two pennies to $1.65. But management reported that the number was better than expected because of lower costs and the positive effect of an insurance recovery. As far as Wall Street estimates were concerned, the bottom line beat by a wide margin. This item says that Carnival bested estimates by $0.07.

Another cool thing is that Carnival narrowed its fiscal-year guidance in a most positive way. Before, the company expected that it would book earnings somewhere between $2.70 and $2.80 per share. Well, now management thinks it'll do between $2.79 and $2.81. That shows confidence in the business, and it looks like the market is pretty happy with the results. Taking a look at the stock at the time of this writing, I see that is up almost 3%, and that volume is decent so far.

I personally would not buy Carnival at this time, however, even though there are some sound elements to this story. It does sport a very good dividend yield of 4%, but it's not close to the 52-week low, and one could argue that the upgraded guidance is confirmation that the stock could be a buy. Still, the market is volatile, the economy is questionable, and energy prices remain a concern. Plus, the earnings release did note some weakness in occupancy levels for advance bookings. I'd be fearful of looking at Carnival before a pullback brings the stock in a little. Long term, though, I do think the company will prosper, since I think it is a great brand in the leisure business.

Disclosure: I own Disney; positions can change at any time.

"If you think filling up an SUV is painful, try footing the bill for a massive 1,000-foot ocean liner -- or in the case of Carnival Corp. (NYSE: CCL), an entire fleet of 84 floating cities," notes value investor Nathan Slaughter.

In his Half-Priced Stocks he explains, "Despite unprecedented fuel costs, the company continues to power forward." Here's his bullish review.

"Last quarter, Carnival shelled out $530 per metric ton for fuel, up sharply from $330 per ton a year ago. And after pumping about 800,000 metric tons, the company rang up a total fuel bill of $425 million.

"For the year, management is expecting fuel costs to come in about $750 million higher than in 2007, which will trim earnings by about $0.92 per share. Fortunately, the company is in a position to absorb those higher costs.

"Over the past three months, two million passengers have boarded a Carnival ship, for an occupancy rate of 104.8% (indicating some berths held more than two guests). And those visitors paid $2.6 billion for their tickets and plunked down another $743 million in the lounges, casinos and gift shops after they arrived on board.

Carnival Corp. (NYSE: CCL), a provider of cruise vacations and competitor of Royal Caribbean (NYSE: RCL), issued its Q2 earnings numbers on Thursday. Revenues rose more than 16% to $3.4 billion. Net earnings were 49 cents a share. That wasn't too impressive, considering that it was a penny better than the previous year's quarter. However, according to Briefing.com, Carnival killed the earnings expectations of analysts by 8 cents. Net sales were also higher than what Wall Street's expectations.

This performance sent the stock up more than 5%. I think investors need to be a little careful here because Carnival's management has become cautious about the next quarter because of energy costs. The company expects earning of $1.56 to $1.58 per share in Q3. Last year's Q3 saw bottom-line income of $1.67 per share. So, growth will not be found in next quarter's report.

Yet, again, the market didn't seem to mind, as it was high off the expectations-beating data. Is Carnival, therefore, a buy? Well, I don't think it's overly expensive considering the P/E ratio and the yield attached to the stock. But the direction of oil prices has me concerned. Not only will that increase costs for Carnival, but it will compete with the discretionary dollars of potential vacationers. I see the valuation case, but the current state of the market makes me reluctant to pull the trigger on this stock. Some would argue that all this is baked into the shares since they did so well yesterday, but I'm not convinced.

Disclosure: I don't own any company mentioned here; positions can change at any time.

The choppy/consolidating (or perhaps worse) market conditions sometimes give the impression that growth plays do not exist, but that is not the case, and one growth company worth reviewing is Carnival Corp.

Carnival Corporation (NYSE: CCL) is the world's largest recreational cruise ship company.

Analysts expect adequate revenue gains for CCL in 2008, primarily on increased capacity. Larger booking increases are expected in Europe, as opposed to North America, which may begin to show the effects of the U.S. economic slowdown. As of first quarter 2008, Carnival had 85 ships with a passenger capacity of 158,000.

Meanwhile, cruise prices should rise modestly, and a likely fuel surcharge will ease the impact of higher fuel costs. Further, analysts also like CCL's rising demand for Caribbean cruises, along with the company's leading market share in leisure cruises. The Reuters FY 2008/FY 2009 EPS consensus estimates for CCL are $3.09 to $3.40.