We live and die one catchphrase at a time. We can't help it. Mantras feel so good as they roll from our tongues. We cling to them because they're catchy, like cotton candy on sticky fingers.

We can be so stupid sometimes.

OK, let me narrow that down. I can be so stupid sometimes. I've been seduced by market poetry. I've accepted a battle cry like "bulls make money, bears make money, but pigs get slaughtered" as a Wall Street truism. But maybe it's time I stick up for this little piggy that went to market.

I understand why bulls make money. There's a historical advantage to being long. Daily downticks and corporate meltdowns show how bears make money, even if it's a trickier practice, given the market's tendency to inch higher over long stretches of time.

But I get lost about this obsession with turning a pig into canned pork product. What's the problem here? Are you a glutton at the feeding trough if you hold onto a company for too long? Of course not. Great investors like Warren Buffett have held winning stocks for generations. Are you piggish because you hold a 10-bagger with the hope that it will roll into a 20-bagger? If so, hold your snout up high, because some other Nervous Nellie cashed out earlier when it was just a five-bagger.

I would argue that "bulls make money, bears make money, pigs make more" is a better slogan. Yes, it sounds hedonistically stubborn. There's a certain stench of Gordon Gekko arrogance in claiming that greedy investors come out ahead. However, history teaches us that there are times when it's good to be a pig.

Investors were snapping up shares of GameStop (NYSE:GME) when it went public five years ago at a split-adjusted price of less than $10 a share. The market disregarded the video game rental chain, figuring that it was Barnes & Noble (NYSE:BKS) trying to shed an uninspiring subsidiary. Big mistake. Consolidation helped strengthen the company's grip on the booming market. GameStop also found a niche in the resell market, where buying and selling used gear is a higher-margin category than its more conventional sales. The stock went on a tear. Even with console struggles on the Xbox 360 and PS3 side, the stock is still a four-bagger for those who bought during its 2002 debut.

Well played, piggies.

When pigs fly
That got me thinking: If that sound bite is flawed, how many other morsels of investing wisdom come with hollow centers? How many people boil down market philosophy to four simple words that can burn them in the end?

Way too many, I'm afraid. My good friend Bill Barker has done a great job of singling out four-word philosophies that work; now I've unearthed my own set of less-fortunate maxims. See if any of these have burned you as badly as they have scorched me in the past.  

The P/E is low
Stocks aren't cheap just because the multiples on their trailing earnings are low. Homebuilders have low price-to-earnings (P/E) ratios on a trailing basis but some pretty sobering markups if we look ahead. Utility stocks may trade at low prices, but the same can be said for their growth prospects. A stock with a low P/E is not necessarily cheap.

The P/E is high
GameStop sported a high P/E ratio through most of its run. Motley Fool Rule Breakers recommendations such as Internet content delivery enabler Akamai (NASDAQ:AKAM) and military and home robotics specialist iRobot (NASDAQ:IRBT) always seem to go for market premiums. The key here is that their bottom lines are growing quickly, or as in the case of iRobot with its spotty profitability, that the growth potential is supporting a healthy markup. You have to go all the way back to 2004 to find the last time that Akamai missed its annual profit target. A stock with a high P/E is not necessarily expensive.

Sell on the news
Speculative investors buy on the rumor and sell when they're right, but where's the joy in that? They took on the risk of a certain event taking place, but they're not going to stick around to enjoy the spoils of victory? You saw this happen when Google went public in 2004, with investors fretting over the moment that the lockup period expired and insiders could begin selling. It failed to happen in a materially damaging way.

You also see this happen every time Panera (NASDAQ:PNRA) seems to bump up against a niche threat like a fast-growing baked eats competitor, minimum-wage hikes, or a low-carb diet fad. Through it all, Panera seems to do just fine despite the revolving door of newbies.

Buy low, sell high
This is probably the most overused tidbit of market jargon. It ignores the obvious: We often don't know what defines too low -- or too high -- until it's too late. Hitting a fresh 52-week low is rarely the sign of a trough. A new 52-week high is unlikely to be a peak. You see this all of the time with companies such as GameStop, Google, and Panera. Fresh highs aren't permanent peaks. If anything, a year later, they often start being referred to as a 52-week low.

All hogs go to heaven
So where does that leave you? I hope you haven't tethered your life to an arsenal of clever, empty words. Few market truisms are universal. Look around long enough, and you'll find more exceptions to the rule for any prolific claim.

Stocks march to their own beats. No one is going out to eat anymore? Tell that to Cheesecake Factory (NASDAQ:CAKE). The casual dining chain has rarely posted negative comps since going public 15 years ago. Lululemon (NASDAQ:LULU) has nearly doubled since going public last month at $18, despite toiling away in the sluggish athletic apparel market.

I don't follow the guidelines in seeking out my next stock purchase. I know that rules are perpetually broken. I'm smarter than that.

OK, let me broaden that a bit. We're smarter than that.

Want a four-word phrase that may make you rich, instead? Why not give Motley Fool Rule Breakers a shot? The newsletter picks promising stocks that are reshaping the competitive landscape. Akamai and iRobot are active recommendations. And even though "there's no free lunch" is another popular four-word phrase, I'll let you in on a free 30-day pass to eat as much as you like.

This article was originally published on April 10, 2007. It has been updated.

Longtime Fool contributor Rick Munarriz doesn't like to speak in four-word sentences. Well, maybe this time. He does not own shares in any of the companies in this story. GameStop is a Stock Advisor pick. The Fool has a disclosure policy.