Is the future for big or sporty gas-guzzlers grim? Not necessarily. It's true that hybrid sales have been soaring, and some 45% of people surveyed "consider gas guzzlers a fashion faux-pas" -- but I wouldn't count on SUVs and luxury cars disappearing any time soon, especially if the price of gas falls.

True, a General Motors (NYSE:GM) survey found that "nearly nine in 10 women would rather talk to a guy in a Prius than a Porsche." How can this be so? Well, one way is to consider that perhaps the women are not interested in the guy as much as the car. They may well be thinking about whether they should buy a Prius themselves, so they are interested in learning from Prius owners.

But the verdict against luxury vehicles is by no means unanimous. A different study found that testosterone levels in both men and women rose after hearing the revving engines of exotic sports cars. We may know that they're gas guzzlers, but some of us gravitate toward them anyway.

What to do
So what does this mean for us investors? Well, it can be useful to look into trends, surveys, and studies as we do our stock research. Sometimes, as with cars, we won't necessarily come to a definite conclusion. But often, all the signs will point toward making a particular investment decision.

For instance, The New York Times recently reported that people are increasingly fixing up older homes instead of buying new ones. That bodes well for Home Depot (NYSE:HD) and Lowe's (NYSE:LOW).

The economic downturn has hurt state revenues, causing many states to look for alternative revenue sources. States like Kentucky and Massachusetts are considering allowing casino development. If they do, demand for casino machines will rise, and so we might want to keep an eye on International Game Technology (NYSE:IGT).

If the government vastly simplifies the tax code, then H&R Block (NYSE:HRB) might see some of its business dry up. (The code currently takes up more than 7,000 pages of text, much of it in fine print.) Both Obama and McCain have spoken of simplifying the code.

The folks at Archstone Consulting expect sales of gift cards to fall by around 5% -- about $1.3 billion -- during this year's holiday season. This will be troublesome news to companies such as Best Buy (NYSE:BBY) and Costco (NASDAQ:COST) that make a lot of money on gift cards.

Before you buy a stock, it's worth looking into the trends that affect it. Sometimes, following a trend can be the push that helps your stock outperform its competition.

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Longtime Fool contributor Selena Maranjian owns shares of Home Depot. Home Depot and Best Buy are Inside Value recommendations. Costco and Best Buy are Stock Advisor picks. The Fool owns shares of Best Buy. Try our investing newsletters free for 30 days. The Motley Fool is Fools writing for Fools.