When confronted with the details of how an Internet or e-mail scam works, it's easy to scratch our heads and say, "But that's so obvious. Who would fall for it?"

Such was the case for a reader named Carmen, who responded by e-mail to my recent column on the "check overpayment scam."

As you may recall, that scam involves someone agreeing to buy an item that is advertised online. The buyer then "accidentally" sends the seller a check for more than the agreed-upon price, and asks the seller to wire the difference back after cashing the check. Problem is, the check is a clever forgery … and that usually isn't discovered until after the seller has sent money to the buyer, thus losing his or her hard-earned cash.

Carmen wrote that people who are faced with this scam should be tipped off long before any checks — real or fake — exchange hands.

"Who, in their right mind, would buy a piece of used furniture without first looking at it? Especially a sofa. Think dog/cat hair, spilled Kool-Aid/soda stains, cookie crumbs ground into the fabric, rips and tears, etc. Are the springs sound? Do the pillows sag? Is there a leg broken/missing?"

I see your point. When I read your e-mail, I imagined my fastidious mother-in-law, who would cringe at the idea of buying a used piece of furniture for those very reasons. But I digress.

Carmen, who had personal experience with such an attempted scam, had more to say, asking why anyone in a far-flung city or state would need to buy a used sofa from Salt Lake City and have it shipped.

"It happened to me, and I quickly e-mailed the supposed 'buyer' with those questions and I never heard from him/her again! I ended up giving the sofa to a needy family. That brought me more satisfaction than anything," Carmen wrote.

That was an excellent way to handle the situation, Carmen. But the questions you raised made me think of other scams I've seen, several of which have been passed along to me by a reader named Gerry. Two of them involve e-mails that supposedly come from the Internal Revenue Service.

The first one says, "After the last annual calculations of your fiscal activity we have determined that you are eligible to receive a tax refund of $592.07." It then provides a Web link to click in order for the refund to "proceed." (It also includes a grammatical error, which I found irritating.)

The other e-mail has the rather ominous subject line of "Notice of Underreported Income" and asks you to review your tax statement on a supposed IRS Web site by clicking on a particular link.