We live and die one catchphrase at a time. We can't help it. Our familiar mantras feel so good as they roll from our tongues. We cling to them because they're catchy.

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 the little piggy that went to market.

I understand why bulls make money. There's a historical advantage to going 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 somewhere in this obsession with turning a pig into canned ham. What's the problem here? Are you a glutton at the feeding trough if you hold on to a company for too long? Of course not. Great investors -- Warren Buffett among them -- 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 scooping up shares of Research In Motion (NASDAQ:RIMM) for less than half of today's price a year ago. The stock wasn't cheap back then, either. The company was already setting the smartphone standard with its BlackBerry wireless device at the time.

However, the market didn't fully appreciate the need for white-collar workers and consumers alike to remain perpetually connected to their email. Just because a company such as Palm (NASDAQ:PALM) couldn't gain traction in the field it pioneered, that didn't mean it was unfit soil. Research In Motion thrived where others failed by building a better mousetrap. Now that RIM is 14 million subscribers strong, handset giants such as Nokia (NYSE:NOK) are out to copy BlackBerry's success.

Well played, piggies.

When pigs fly
That got me thinking: If that soundbite is flawed, how many other morsels of investing wisdom have hollow centers? How many people reduce 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 whether 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 ratios on a trailing basis, but they also have 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"
Research In Motion sported a high P/E ratio through most of its run. Suntech Power (NYSE:STP) -- a Motley Fool Rule Breakers recommendation -- rarely trades at a market discount. Everyone knows that the company's solar cells will become even more popular in time. The same trend has made fellow sun worshippers Evergreen Solar (NASDAQ:ESLR) and LDK Solar (NYSE:LDK) such popular stocks. You pay up for that kind of respect, if only because someone will pay even more than you later on.

Stay ahead of the traffic, and the numbers in your rearview mirror can be deceiving. 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 that a certain event would take place, but they're not going to stick around to enjoy the spoils of victory? You're seeing that happen now with Akamai, as it wins patent battles with smaller competitors. Investors who think the good news is the end of the gravy train fail to realize that court victories have long-reaching implications. In this case, those wins may be turning a cutthroat industry into one in which Akamai has a sustainable advantage.

"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. If anything, a year later, that high often starts being referred to as a 52-week low. You see this happening all of the time with companies such as Research In Motion.

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 eating out anymore? Tell that to California Pizza Kitchen (NASDAQ:CPKI). The casual-dining chain upped its outlook earlier this week on the heels of better-than-expected sales. No one is shopping anymore? Get thee to a mall. Take a page out of Peter Lynch's playbook -- find the crowded chains, and follow up your findings with a little due diligence.

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 service picks promising stocks that are reshaping the competitive landscape. Suntech Power and Akamai are active recommendations. And even though "there's no free lunch" is another popular four-word phrase, we'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. Palm is a Stock Advisor pick. Suntech and Akamai are Rule Breakers selections. The Fool has a disclosure policy.