MOST READ: 5 Dumbest Things on Wall Street

3. Marriott: Pretty Vacant

Even as Wall Street has been bubbling with talk of a battered and fried consumer, an oblivious Marriott (MAR Quote) kept building its hotel empire in a weak economic environment. Supply quickly outstripped demand, leaving Marriott with more uninhabited rooms than the Bates Motel after a bad night.

The severity of Marriott's missteps became apparent Thursday when it reported a 24% year-over-year drop in second-quarter earnings. Adjusted earnings beat Wall Street's lowered expectations, but gloomy guidance sent the stock spelunking to levels unseen since 2004.

CEO J.W. Marriott Jr. said that "business conditions have deteriorated" in the U.S. market, and he expects "weak economic growth and soft lodging demand" to continue into 2009. Apparently, the notion that people forego vacations when they're feeling a pinch in the pocketbook eluded Marriott.

In fairness, the hotelier's revenue per available room -- known in industry lingo as revpar -- increased 5.6% globally, thanks to healthier markets in Southeast Asia and the Middle East. Unfortunately for Marriott, though, most of its hotels are stateside, where revpar grew a meager 1.4%.

In an effort to right the ship, Chief Financial Officer Arne Sorensen outlined "contingency plans," including changes to the hotel's restaurant menus, hosting more banquet-style events to bolster non-room sales, hiring freezes and forced vacations for workers. All well and good, but those initiatives won't offer the company much headway with the extra empty rooms it now has to maintain.

Marriott could've benefited from a simple rule of business: If people don't want what you're selling, don't try to give them more of it.

Dumb-o-meter score: 91. When the going gets tough, the tough don't go on vacation.