Like a yo-yo dieter, Weight Watchers International (NYSE:WTW) continues to gain and lose market value. With investors less than impressed by third-quarter results and guidance, the stock price has slimmed down by as much as 15% in the past week. Since management always seems to find the bright side of things without really ever taking responsibility for shortfalls, I doubt that I'll be looking to this company to fatten my wallet on the long side.

Revenue rose just 5% in the quarter as modest growth in North America and double-digit online revenue counterbalanced declines in the international business. Attendance trends were also rather unimpressive: U.S. attendance rose 3%, international attendance fell 5%, and total attendance declined about 1.5%. What's more, overall product revenue dropped 11% for the quarter.

The good news, such as it is, is that margins are good and getting better. Gross margin improved by 420 basis points, and the operating margin improved by nearly 300 basis points. That, in turn, led to an increase of 15% in the company's operating income, though adjusted net income growth was more on the order of 11%.

In some ways, Weight Watchers strikes me as a trap for value investors along the lines of how labels like "low fat" or "reduced calories" can ensnare diet-conscious shoppers. See, this company produces copious amounts of free cash flow and sports a truly eye-popping return on invested capital. Yet missteps by management have led to shaky earnings performance and an erratic stock.

Topping it off, management tried to blame part of the third-quarter malaise in recruitment on Hurricane Katrina. To me, this is bunk. Yes, people may have watched their televisions a bit more than usual for a few days, but I do not accept the idea that the storm caused some fundamental (even if temporary) shift in behavior across the country. In other words, I just don't buy the notion that overweight men and women in New York, Seattle, and Chicago stayed away from Weight Watchers meetings because a hurricane devastated Louisiana, Mississippi, and Alabama.

I truly do appreciate the appeal of this company. There are few publicly traded plays on weight loss, with tiny eDiets (NASDAQ:DIET), high-growth/high-valuation NutriSystem (NASDAQ:NTRI), troubled Bally (NYSE:BFT), and Life Time Fitness (NYSE:LTM) constituting the bulk of the non-pharmaceutical ideas. Nevertheless, I just don't have much faith in current management, and for me, that trumps numbers in this case.

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Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares).