A pair of high school kids did a DNA-barcode test on New York City sushi and found that one-quarter of the fish they tested was really a cheaper species than what the seller said. The kids, Kate Stoeckle and Louisa Strauss, got some help from Eugene Wong, a graduate student at the University of Guelph in Ontario, but these new quick DNA tests show both how easy testing is becoming -- and how prevalent fish fraud is.

The girls sampled 60 different kinds of sushi, then Wong ran them up against the growing library of DNA at the Fish-Barcode of Life. He could get a reading on 57 samples and found that 14 of them were mislabeled. And all the labeling errors went in the seller's favor, making the fish more expensive.

The most mislabeled fish was red snapper: seven of nine samples (77%) were really something else. Most egregiously, some of it was really the endangered Acadian redfish. Their results are no fluke. This spring the Chicago Sun-Times did a great investigation on Chicago sushi and found all 14 of its samples of red snapper were fake, mostly the cheaper tilapia. They say a congressional report found that 37% of fish and 80% of red snapper sold in America is mislabeled. That's consistent with a 2004 University of North Carolina study that found 75% of red snapper was fake.

One of the great joys of my life is marketing. To put it simply, I love watching companies desperately try to convince me that I can't live without this item or that item, that my entire life will be better if I use this product or that product.

Generally, marketers are pretty straight about their purpose: they want me to buy their product, and will make outrageous claims, pay for expensive celebrity endorsements, and spend a fortune on slick commercials in order to get my money. I, in return, generally ignore them, make my purchases based on price, tradition, and quality, and go on my merry way.

As much fun as it is to play this cat-and-mouse game, there's a time when even the savviest consumer has to acknowledge the value of truth in advertising. For me, that moment happened when I heard about the uproar over condom marketing. Here's how it played out:

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Meijer, a grocery store mainly located in the Midwest, has begun offering select prenatal vitamins for free in the pharmacy! My local ad doesn't specify which vitamins are included, but the press release identifies several name brands; "NatalCare Plus, Ultra Natal Care, Natal Care Glosstabs, Advanced NatalCare, and NataTab Rx."

You can get up to a 30-day supply on one visit and you can only take advantage of this in-store.

If this proves to be anything like the move most retailers made last year to offering free or $4 antibiotics then I would expect Target and Walmart to join in the offer pretty soon. This deal is of course, designed to get you into the store and capture your weekly grocery bill. Savvy shoppers may be able to talk Walmart or other local store into price matching the offer to cut down on multiple trips if you regularly visit another store.

One of the thrills of pregnancy is experiencing your body change week to week as it miraculously creates a new human being. One of the many challenges of pregnancy is trying to keep yourself clothed and looking neat while you morph into a whole new shape.

It's tempting to wear nothing but sweats and oversized t-shirts. But feeling good about how you look can make pregnancy more fun -- all that friendly chit chat doesn't seem quite so intrusive, for example, if you feel confident about your appearance, I'd argue. And it most likely takes high-quality maternity clothes to do the trick.

That's where your local thrift shop can come in handy. Fact is, maternity clothes are expensive. And you'll need a lot of them to make it through a pregnancy. Most pants or shirts only fit for a month before you're onto the next size. You can fill up your closet at your local thrift shop without spending a fortune. Then, when they don't fit anymore or you have your baby and can't stand the sight of the maternity clothes anymore, you can get rid of them without buyer's remorse.

One caveat: You may have to hunt around or get your veteran thrifter friends to be on the lookout for you. It seems the best maternity wear is picked up right quick in thrift shops these days. And its often only the best run shops that take the time to separate it out from the rest of the duds. Shopping for maternity wear can be hard work at thrift stores, but it will likely be well worth the effort.

This post was written as part of a series on how to thrift shop smarter. Read more on what to buy, and not to buy, at thrift stores.