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

Company

Closing Price

CAPS Rating (5 max)

% Change

52-Week Range

TriMas (NYSE: TRS)

$5.66

***

(16.40)

$5.23-$16.51

Global Partners (NYSE: GLP)

$22.50

*****

(14.45)

$20.72-$41.29

Noven Pharmaceuticals (Nasdaq: NOVN)

$10.54

***

(10.53)

$8.71-$26.15

Sealy (NYSE: ZZ)

$7.75

*

(5.02)

$7.40-$18.13

General Motors (NYSE: GM)

$20.31

*

(2.96)

$19.00-$43.20

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

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

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 86,000-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 General Motors, which fell when analysts at Morgan Stanley, who had expected the carmaker to post a 2008 profit, reversed their thinking yesterday. Morgan also cut its full-year U.S. auto sales forecast by 500,000 vehicles.

But of course it's worse than that. Unlike Ford (NYSE: F), GM last produced positive free cash flow in 1993. Apparently that's not about to change.

Worser
Next up is Sealy, which, like peer Select Comfort (Nasdaq: SCSS), is suffering from lower margins and declining returns on capital. Yesterday, someone -- finally -- took the fall for the fall. CEO David McIlquham has left the company.

It's a good bet he was fired. Quoting from a statement:

Mr. McIlquham, along with the Board of Directors, has determined that it is in the best interest of the Company to seek new leadership to achieve the Company's long-term goals and initiatives. Mr. McIlquham will pursue new opportunities and spend more time with his family.

Touching ... in a don't-let-the-door-hit-you-on-the-way-out sort of way.

Worst
But our winner is Noven Pharmaceuticals, which said that the SEC is questioning the way the firm accounts for deferred revenue and, as a result, it is asking to delay filing its full fourth-quarter results.

Don't hold your breath waiting. Or, for that matter, expect better news when the report is finished. Preliminary figures show that revenue and profit came in lower than analysts expected.

It's a pattern we may have to get used to. As Foolish colleague Brian Lawler pointed out, Noven's competitive advantage in drug development isn't exactly quantifiable:

Because Stavzor is not a new molecular entity, Noven will face a much harder time trying to differentiate it from the hordes of generic drugs that will be competing against Depakote in the next few years. To be clear, Stavzor is not a generic version of Depakote because it is a slightly different oral form of the drug, though it will probably have very similar efficacy and safety effects to Depakote.

Depakote is a $1.2 billion compound developed by Abbott Laboratories. Whoops.

Noven Pharmaceuticals and its delayed date with a possibly disastrous destiny ... Thursday'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 Tuesday with more stock horror stories.

Fool.com and Rule Breakers contributor Tim Beyers, who is ranked 16,942 out of more than 86,000 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.

Select Comfort is a Motley Fool Hidden Gems recommendation. Check out the entire portfolio with a 30-day free pass to the service. There's no obligation to subscribe.

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