You would think that putting together an office-appropriate wardrobe would be common sense, but we know from careful observation that this definitely isn't the case.

Of course, every occupation requires a different kind of wardrobe and some work environments are more casual than others, so we've chosen to focus on what not to wear to work at the average office job. While these rules don't apply to everyone (strippers or construction workers, for example), they certainly ring true for most jobs.

If you'd like to keep your job during these tough economic times, or even garner that big promotion, you've got to look the part (whether you like it or not).

To us, these are the top five work wardrobe catastrophes to avoid.

First up, be sure to avoid a denim disaster ...

denim jeans at work casual day

No. 5: Avoid wearing denim

Denim is OK for "Casual Friday" (employer permitting), but use caution when wearing jeans to work.

Modern jean styles include tight legs and low rises. Unless you're shaped like Kate Moss, you should never try to rock a pair of skinny jeans at work. And while you don't want to sport mom jeans, your boss isn't likely to be impressed by your whale tale.

This Friday, how about a pair of tasteful denim trousers? They say professional and trendy, but feel casual and comfy. Or dress down without resorting to denim with a pair of khaki trousers and a simple blouse or more casual dress shirt for the guys.

Finally, tasteful denim is OK for Friday, but don't commit this fashion crime during the rest of the workweek, and certainly NEVER wear jeans to a job interview (you might as well put "idiot" on your resume).

Next, this little piggy lost her job ...

feet in sandals

No. 4: Be sure to wear the right shoes

Even if you've got a real shoe fetish, certain types of footwear should never make their way into the office.

Most notably, anything that shows off your toes. A slight peep-toe pump might be acceptable in some offices (although older generations might question its appropriateness), but flip-flops or Birkenstocks should never be a part of your work wardrobe.

Other major fashion footwear no-no's include sneakers, tennis shoes, clogs and Crocs.

Unless you're a nurse, save the Reeboks for the gym and opt for a nice classy pair of pumps or some sensible dress shoes. If you hoof it to work (great for your bod and the environment!), stash a pair of pumps or dress shoes in your shoulder bag and switch out your sneaks when you get to work.

Our next tip shows that you're better off leaving the lounging for home ...

woman in sweatpants loungewear

No. 3: Leave workout clothes, loungewear at home

Workout gear and loungewear have regained popularity in recent years, but if your yoga pants make their way into your work cubicle, you're going to have a problem.

Loungewear might be fine for the grocery store and running errands (although celebrity fashion experts Clinton Kelly and Stacy London would definitely call it criminal), but it's never acceptable for the office (we don't care where you work).

Even "Casual Friday" should never get that casual.

A good rule of thumb for casual wear at work: If you wear it to the gym or to bed, you should never wear it to the office.