Call it a "whatchootalkin'bout, Willis?" moment.

Today, the Conference Board said that Americans were more optimistic about the economy in January than they have been for more than three years.

What's so crazy about that? Well, just try and square it with the reality about what's happening to the American pocketbook.

We found out yesterday that in 2005, for the first time since the Great Depression, Americans spent more money than they earned for an entire year.

This morning, we discovered that in 2005, real wages decreased. For the first time since 1996, wages increased by an amount that failed to cover inflation. (It's sad to note that, in light of those wage figures, the Conference Board's survey shows that 21% of Americans believe their income will increase in the months ahead.) Yet consumers are convinced we're in the best of times, and they're willing to bet money (that they don't seem to have) on that belief?

Hey, I don't understand it either.

What I do understand is that things can't continue this way forever. For quite a while, American shopping seems to have been fueled by speculative gains on real estate-swapping, as well as that related trick, an "equity" loan taken out and spent on stuff -- the incredible live-in ATM.

But in the absence of real wage growth, how much longer will these good times roll? The housing bubble -- which the "where's my 6%?" home-selling industry used to take such pains to deny -- is already starting to hiss, making it increasingly likely that "mass affluent" Americans may have their mass and affluence handed to them by falling home prices. My colleague Nate Parmelee recommends the Boston-area real estate listings for an example of what this looks like.

But what does this mean for investors? I don't have a lot of time and patience for complete top-down investing, but in the face of such an obvious disconnect between American perceptions and reality, it can't hurt to keep an eye on the macro.

For my part, I'm only more convinced that bottom-up investors should be looking for themes. What are people going to keep using if and when some hurt comes home? I have a hard time seeing demand -- or prices -- for oil drop a whole lot. You might find value in the big pumpers like ExxonMobil (NYSE:XOM) or alt-oil Suncor Energy (NYSE:SU), or in the pick-and-shovelish plays like Carbo Ceramics (NYSE:CRR) or TODCO (NYSE:THE).

When tough times hit, there's only so much that can be stripped from the budget. That's why I also like to look for cheap foodies -- Arden Group (NASDAQ:ARDNA) is one of my favorites -- and food makers and consumer products firms like Procter & Gamble (NYSE:PG) or Kraft (NYSE:KFT), especially those that can be picked up on the cheap.

It doesn't hurt to stay prepared.

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Seth Jayson is confident that consumers are nuts, but then, he did spend last Sunday at a mall. At the time of publication, he had shares of Arden Group, but no positions in any other firm mentioned. View his stock holdings and Fool profile here. Fool rules are here.