As weak as consumer spending is, this year's Super Bowl ads are still the most expensive in history at $3 million for a 30-second spot: $100,000 per second.

Even though General Motors (NYSE: GM) and other struggling former mainstays are bowing out of the Super Bowl this year, 90% of the advertising spots for the game are already sold. Denny's (NASDAQ: DENN) purchased a spot in the less-expensive third quarter -- an interesting decision given that that company has seen its stock price decline by more than two-thirds since late 2007. A $3 million ad represents about 2% of that company's market cap, not including production expenses.

Still, some experts say that Super Bowl ads are actually relatively affordable for the amount of eyeballs they attract: 2.7 cents per view compared with 5.6 cents for the Oscars.

Still: Is it really a good idea for companies to shell out millions of dollars to advertise to consumers who don't have any money to spend? For those that can easily afford it and need to keep their brands in the spotlight it makes sense. But for more marginal cases like Denny's, I'm not so sure.

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