A recent report from msnbc.com tells the cautionary tale of online shoppers who were intrigued by ads offering "free samples" of a new kind of toothpaste. Many of these people clicked the ad to receive a sample – and instead lost hundreds of dollars.

After entering their credit card numbers for "shipping costs," victims found that monthly deductions of $58 showed up on their accounts.

Warning Signs & Red Flags

This scam had elements in common with other online scams we've written about here before. Generally speaking, any of the following should signal to you that the "free" offer in question is most likely a way to take your money.

• Minimal payment upfront. In the case most recently documented (in the article), victims were asked to pay a five dollar shipping charge.
• Use of credit card. If an offer requires you to enter your credit card information, close that screen and walk away from the computer. Any truly free offer should not involve payment.
• Fine print. Many Internet users skip right over "terms of agreement" texts, often because they're long and boring-looking. But that section contains important information – and it may reveal the "free" offer to be a costly deal.

The Internet can be difficult to navigate, because nefarious links often appear on otherwise trustworthy sites – in fact, in the msnbc.com story, victims reported just such an occurrence.

So take caution: Just because you trust a site doesn't mean you can trust the ads that appear on it.

Struggling financially? Bankruptcy may be right for you.

What to Look Out For

Online scams often sound tempting to consumers because they're designed to appeal to our weaknesses. Products commonly seen as part of online scams include:

• Beauty and weight-loss products: Supplements, diet systems and even whitening toothpaste may be presented in "free trial" form.
• Work at home offers: Bogus opportunities for self-employment (with guaranteed hefty paychecks) crop up frequently.
• Fads and trends: Products or services that allow you to sample a new trend for "free" can be fraudulent, too.

Remember: if something is really worth having, it's worth paying for. And if you wouldn’t pay for it in the first place, you really don't want to overpay in hidden costs and "membership fees" that offer you little or no real benefit.

Tags: credit cards, online fraud, scams