NEW YORK (CNN/Money) - The word "unethical" has gotten quite a workout in the past few years. From Enron to the mutual fund trading scandal, we've been slammed with story after story of corporate fat cats bilking the little guy.

Their aerobic malfeasance makes it easy to feel like we're angels by comparison. After all, you didn't decimate anyone's nest egg through smoke-and-mirror dealings or undermine the public's trust in important institutions.

But that doesn't mean we always act ethically in everyday money matters. From telling little white lies on our taxes to pocketing extra change to hiding purchases from a mate, chances are you and I have slipped up a few times.

The truth is, "we all have done something unethical," said John C. Maxwell, author of "There's No Such Thing as Business Ethics."

That's because one key driver behind ethical lapses is selfishness, Maxwell said. And no one is immune from the desire to act selfishly.

Here's one working definition of ethical: Choosing to do the "right" thing when you consider taking an action that will affect another person's or group's rights or well-being. That's from Bruce Weinstein, founder of TheEthicsGuy.com and author of "What Should I Do? 4 Simple Steps to Making Better Decisions in Everyday Life."

For his part, Maxwell believes the Golden Rule – do unto others as you'd have them do unto you -- is as good a guideline as any when deciding the most ethical way to act.

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So if you're selling a house and you're tempted not to disclose a flaw in the home, you might choose to disclose it anyway since that's how you'd like to be treated as a buyer.

Or say you find a money clip with a wad of cash, as Weinstein once did. You might want to keep it -- after all, who would ever know? But you might decide to report it to the police instead since that's what you'd want someone to do for you. (Weinstein told the police he'd be happy to return the clip with the cash to the person who could accurately describe it.)

Now you may not get things right every time. And no one is suggesting there's always one right answer for every situation.

But striving to act ethically is worthwhile, not only because we make life better for others but also because it's easier to live with ourselves in the long run. (Chalk up another one for selfishness?)

To test your ethical muscle in everyday money matters, consider what you'd do in the following scenarios.

You just bought something expensive that your spouse would consider a waste. Are you ethically obligated to tell your mate about the purchase?

a) Yes

b) No

c) It depends

In Weinstein's view, it depends on the kind of relationship you've negotiated with your spouse, and on whether you share a joint bank account.

You should certainly tell your mate if you share an account, since it's his or her right to know. And you should probably 'fess up if you've agreed to be open about your finances.

Give yourself some points if you picked c).

When you itemize deductions on your tax return, you:

a) Sometimes inflate what you paid for a deductible expense

b) Occasionally make up a deduction

c) Never include expenses for which you don't have receipts

d) Make a modest estimate of an expense you know you incurred but for which you don't have a receipt

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Making up deductions or inflating the amount of certain expenses is, well, dishonest. "If you're lying, you're lying," Maxwell said.

On the other hand, he said, if you know you incurred an expense but can't find the receipt, there's no reason not to make a claim for it.

So, consider yourself in the ethical clear if you chose d).

When buying food at a gourmet store, you get $10 more in change than you're owed. You:

a) Give the cashier back the extra $10.

b) Pocket the $10, figuring the store overcharges anyway.

c) Keep the $10, figuring the store has probably stiffed you in the past.

"By not giving the money back, it will almost always have serious repercussions. It will not go unnoticed. ... It will come out of the (clerk's) pocket or he may get fired or reprimanded," Weinstein said.

Kudos if you chose a).

You do a freelance project for a big company and when you (finally) receive your paycheck, you notice the company overpaid you. You:

a) Keep the change, figuring the company isn't hurting for bucks, and it's not like you're being paid top dollar anyway.

b) Alert the accounting office to the error.

c) Figure that sending it back would just further delay your getting compensated.

"Returning the money is the only appropriate response, since the money is not ours to keep," Weinstein said. "It's what Gomer Pyle's grandmother referred to as 'ill-gotten gains.' ... The harm to the company that would occur if we kept the money may in fact be minimal; the duty to return it is ground in the principle of justice rather than beneficence ... or non-maleficence (the duty to avoid harming others)."

But you knew that and chose b), right?

Jeanne Sahadi writes about personal finance for CNN/Money. She also appears regularly on CNNfn's "Your Money," which airs weeknights at 5 p.m. ET. Please let her know what you think about the issues raised in this column by e-mailing her at everydaymoney@cnnmoney.com.