Bad days. We all have them; some of us deserve them. Here are five stocks whose naughty ways drew investors' scorn on Tuesday:

Company

Closing Price

CAPS Rating (out of 5)

% Change

52-Week Range

Collective Brands (NYSE: PSS)

$10.46

***

(15.03%)

$9.14-$37.20

Playboy (NYSE: PLA)

$7.49

*

(9.32%)

$7.07-$12.00

Qwest (NYSE: Q)

$5.04

***

(5.97%)

$4.38-$10.45

WebMD (Nasdaq: WBMD)

$31.74

*

(5.39%)

$21.86-$63.49

US Airways (NYSE: LCC)

$8.03

*

(3.49%)

$6.10-$36.81

Sources: The Wall Street Journal, Yahoo! Finance, Motley Fool CAPS.

Naughty?
Well, OK, we can't exactly call these stocks naughty. There are days when five-star winners and newsletter recommendations appear here. Today isn't one of those days.

But, if you're an investor, you'll have plenty of bad days. The trick is to avoid dating -- or, worse, marrying -- your losers. That's why I listen when our 100,000-person-strong Motley Fool CAPS community of stock pickers speaks with a poor rating or a negative pitch. You should, too.

Thus, here is today's list of the worst stocks in the world.

Worse
We begin with Collective Brands, which suffered a stinging loss in its patent suit with adidas. If the verdict holds, the company formerly known as Payless Shoe Source could be on the hook to pay a $305 million judgment.

Analysts wonder if that's too draconian. Collective Brands, after all, has failed to record $300 million in sales of its allegedly infringing brands over the past seven years, according to researchers at JPMorgan Chase.

We can't know how the courts will respond to Collective Brands' request to set aside the verdict. What we do know is that management intends to fight on, and fighting costs money. Not good news for a struggling retailer.

Worser
Next up is US Airways, which, like industry peer and rumored merger partner UAL (Nasdaq: UAUA), reported lower traffic for April.

Actually, it's worse than that. US Airways reported a 2% decline in revenue passenger miles, a 2.6% decline in capacity, and a slightly higher load factor (83.2%, according to a company statement).

Translation: US Airways is flying less with fuller planes.

With oil now above $122 a barrel, that's probably necessary. Just don't expect passengers to like it much. Or at all.

Worst
But our winner is Qwest, which on Tuesday reported a 35% decline in total net income. Earnings were down 25% on a per-share basis.

Plenty of companies are experiencing weakness, though. The economy is that bad. What makes Qwest special? Two things. First, management is standing by existing guidance for flat 2008 revenue even as first-quarter sales declined by 1%. Do the math. If revenue was down in Q1, Qwest, burdened with unreasonable costs, will have to find growth in succeeding quarters to meet its full-year target.

I doubt it will -- thanks to the second reason Qwest makes today's list: It lacks differentiation by way of a wireless service. Or at least one it owns. Qwest says it will resell Verizon's (NYSE: VZ) wireless offerings to its customers.

Oh, goody.

Qwest and its never-ending quest to tread financial water ... Tuesday's worst stock in the CAPS world.

Do you agree? Disagree? Let us know what you think by signing up for CAPS today. It's 100% free to participate.

I'll be back next Tuesday with more stock horror stories.

Fool contributor Tim Beyers, who is ranked 14,952 out of more than 100,000 participants in CAPS, hopes that Keith Olbermann doesn't mind the blatant theft of his "Worst Person in the World" segment from Countdown. Remember, Keith, imitation is the sincerest form of flattery.

Playboy is a Rule Breakers recommendation. JPMorgan Chase is an Income Investor pick. Try these market-beating services free for 30 days. There's no obligation to subscribe.

Tim didn't own shares of any of the stocks mentioned in this article at the time of publication. The Motley Fool's disclosure policy thinks cooked spinach is the worst veggie in the world.